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Exhibit 1.2

Huntsman Corporation

Shares(1)
Mandatory Convertible Preferred Stock
($                par value)
Underwriting Agreement

New York, New York
, 2005

Citigroup Global Markets Inc.
Credit Suisse First Boston LLC
Deutsche Bank Securities Inc.
Merrill Lynch, Pierce, Fenner & Smith Incorporated
as Representatives of the several Underwriters,
c/o Citigroup Global Markets Inc.
388 Greenwich Street
New York, New York 10013

Ladies and Gentlemen:

        Huntsman Corporation, a corporation organized under the laws of Delaware (the "Company"), proposes to sell to the several underwriters named in Schedule I hereto (the "Underwriters"), for whom you (the "Representatives") are acting as representatives, 5,000,000 shares of      % Mandatory Convertible Preferred Stock, $0.01 par value ("Mandatory Convertible Preferred Stock") convertible into common stock, par value $0.01 per share ("Common Stock") of the Company (the "Underwritten Securities"). The Company also proposes to grant to the Underwriters an option to purchase up to 750,000 additional shares of Mandatory Convertible Preferred Stock to cover over-allotments (the "Option Securities"; the Option Securities, together with the Underwritten Securities, being hereinafter called the "Securities"). The Securities will be established by the Certificate of Designations, Rights and Preferences of the Mandatory Convertible Preferred Stock of the Company identified in Annex A hereto (the "Certificate of Designations").

        The Company also proposes to offer concurrently with the offering of the Securities, pursuant to a separate underwriting agreement to be entered into by the Company and the Underwriters, 55,681,819 shares of Common Stock and to grant to the Underwriters an option to purchase up to 8,352,273 additional shares of Common Stock to cover over-allotments.

        Prior to the completion of this offering and the concurrent offering of Common Stock, the Company and the Selling Stockholder will complete a series of reorganization transactions (the "Reorganization Transactions"). The Reorganization Transactions will include the following transactions: (a) a wholly owned subsidiary of the Company will merge with and into Huntsman Holdings Preferred Member, LLC ("HH Preferred Member"), whereby the former members of HH Preferred Member will receive Common Stock in exchange for their membership interests of HH Preferred Member; (b) a wholly owned subsidiary of the Company will merge with and into Huntsman Holdings LLC ("Huntsman Holdings"), whereby the former members of Huntsman Holdings, other than HH Preferred Member, will receive Common Stock in exchange for their membership interests of Huntsman Holdings; and (c) MatlinPatterson Global Opportunities Partners, L.P., MatlinPatterson Global Opportunities Partners (Bermuda) L.P., MatlinPattesron Global Opportunities Partners B, L.P. and Huntsman Family Holdings Company LLC will cause the contribution of any Common Stock


(1)
Plus an option to purchase from the Company additional Securities to cover over-allotments.

received by either entity as a result of (a) and/or (b), above, to HMP Investments Trust. A list of agreements pursuant to which the Reorganization Transactions will be completed is set forth on Schedule II hereto (collectively, the "Reorganization Agreements").

        The Company will use a portion of the proceeds of the sale of the Securities and the concurrent offering of Common Stock to purchase U.S. treasury securities that the Company will deposit with the Collateral Agent, as defined in the Pledge, Assignment and Collateral Agency Agreement (the "Pledge Agreement") dated as of February       , 2005, between the Company and Citibank, N.A., acting as the collateral agent (the "Collateral Agent"), for the benefit of the holders of the Securities, as collateral to secure the Company's obligations to pay dividends on the Securities.

        To the extent there are no additional Underwriters listed on Schedule I other than you, the term Representatives as used herein shall mean you, as Underwriters, and the terms Representatives and Underwriters shall mean either the singular or plural as the context requires. The use of the neuter in this Agreement shall include the feminine and masculine wherever appropriate. Certain terms used herein are defined in Section 17 hereof.

1.     Representations and Warranties.

        (i)    The Company represents and warrants to, and agrees with, each Underwriter as set forth below in this Section 1.

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        Any certificate signed by any officer of the Company and delivered to the Representatives or counsel for the Underwriters pursuant to this Agreement on the Closing Date or any settlement date for the Option Securities shall be deemed a representation and warranty by the Company, as to matters covered thereby, to each Underwriter.

        2.    Purchase and Sale.    (a) Subject to the terms and conditions and in reliance upon the representations and warranties herein set forth, the Company agrees to sell to each Underwriter, and each Underwriter agrees, severally and not jointly, to purchase from the Company at a purchase price of $                  per share, plus accrued dividends, if any, with respect to the Securities from                        , 2005 to the Closing Date, the amount of the Underwritten Securities set forth opposite such Underwriter's name in Schedule I hereto.

        (b)   Subject to the terms and conditions and in reliance upon the representations and warranties herein set forth, the Company hereby grants an option to the several Underwriters to purchase, severally and not jointly, up to 750,000 Option Securities at the same purchase price per share as the Underwriters shall pay for the Underwritten Securities. Said option may be exercised only to cover

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over-allotments in the sale of the Underwritten Securities by the Underwriters. Said option may be exercised in whole or in part at any time on or before the 30th day after the date of the Prospectus upon written or telegraphic notice by the Representatives to the Company setting forth the number of shares of the Option Securities as to which the several Underwriters are exercising the option and the settlement date. The maximum number of Option Securities to be sold by the Company is 750,000. The number of Option Securities to be purchased by each Underwriter shall be the same percentage of the total number of shares of the Option Securities to be purchased by the several Underwriters as such Underwriter is purchasing of the Underwritten Securities, subject to such adjustments as you in your absolute discretion shall make to eliminate any fractional shares.

        3.    Delivery and Payment.    Delivery of and payment for the Underwritten Securities and the Option Securities (if the option provided for in Section 2(b) hereof shall have been exercised on or before the third Business Day prior to the Closing Date) shall be made at 10:00 AM, New York City time, on February       , 2005, or at such time on such later date not more than three Business Days after the foregoing date as the Representatives shall designate, which date and time may be postponed by agreement between the Representatives, and the Company or as provided in Section 9 hereof (such date and time of delivery and payment for the Securities being herein called the "Closing Date") at the offices of Skadden, Arps, Slate, Meagher & Flom, LLP, Four Times Square, New York, New York 10036. Delivery of the Securities shall be made to the Representatives for the respective accounts of the several Underwriters against payment by the several Underwriters through the Representatives of the purchase price thereof or upon the order of the Company by wire transfer payable in same-day funds to the accounts specified by the Company. Delivery of the Underwritten Securities and the Option Securities shall be made through the facilities of The Depository Trust Company unless the Representatives shall otherwise instruct.

        If the option provided for in Section 2(b) hereof is exercised after the third Business Day prior to the Closing Date, the Company will deliver the Option Securities (at the expense of the Company) to the Representatives, at 10:00 AM, New York City time, on the date specified by the Representatives (which shall be within three Business Days after exercise of said option) for the respective accounts of the several Underwriters, against payment by the several Underwriters through the Representatives of the purchase price thereof or upon the order of the Company by wire transfer payable in same-day funds to the accounts specified by the Company. If settlement for the Option Securities occurs after the Closing Date, the Company will deliver to the Representatives on the settlement date for the Option Securities, and the obligation of the Underwriters to purchase the Option Securities shall be conditioned upon receipt of, supplemental opinions, certificates and letters confirming as of such date the opinions, certificates and letters delivered on the Closing Date pursuant to Section 6 hereof.

        4.    Offering by Underwriters.    It is understood that the several Underwriters propose to offer the Securities for sale to the public as set forth in the Prospectus.

        5.     Agreements.

        (i)    The Company agrees with the several Underwriters that:

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        6.    Conditions to the Obligations of the Underwriters.    The obligations of the Underwriters to purchase the Underwritten Securities and the Option Securities, as the case may be, shall be subject to the accuracy of the representations and warranties on the part of the Company contained herein as of the Execution Time, the Closing Date and any settlement date pursuant to Section 3 hereof, to the accuracy of the statements of the Company made in any certificates pursuant to the provisions hereof, to the performance by the Company of its obligations hereunder and to the following additional conditions:

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        If any of the conditions specified in this Section 6 shall not have been fulfilled when and as provided in this Agreement, or if any of the opinions and certificates mentioned above or elsewhere in this Agreement shall not be reasonably satisfactory in form and substance to the Representatives and counsel for the Underwriters, this Agreement and all obligations of the Underwriters hereunder may be canceled at, or at any time prior to, the Closing Date by the Representatives. Notice of such cancellation shall be given to the Company in writing or by telephone or facsimile confirmed in writing.

        The documents required to be delivered by this Section 6 shall be delivered at the office of Skadden, Arps, Slate, Meagher & Flom LLP, counsel for the Underwriters, at Four Times Square, New York, New York, 10036, on the Closing Date.

        7.    Reimbursement of Underwriters' Expenses.    If the sale of the Securities provided for herein is not consummated because any condition to the obligations of the Underwriters set forth in Section 6 hereof is not satisfied, because of any termination pursuant to Section 10 hereof or because of any refusal, inability or failure on the part of the Company to perform any agreement herein or comply with any provision hereof other than by reason of a default by any of the Underwriters, the Company will reimburse the Underwriters severally through Citigroup Global Markets Inc. on demand for all out-of-pocket expenses (including reasonable fees and disbursements of counsel) that shall have been incurred by them in connection with the proposed purchase and sale of the Securities.

        8.    Indemnification and Contribution.    (a) The Company agrees to indemnify and hold harmless each Underwriter, the directors, officers, employees and agents of each Underwriter and each person who controls any Underwriter within the meaning of either the Act or the Exchange Act against any and all losses, claims, damages or liabilities, joint or several, to which they or any of them may become subject under the Act, the Exchange Act or other Federal or state statutory law or regulation, at common law or otherwise, insofar as such losses, claims, damages or liabilities (or actions in respect thereof) arise out of or are based upon any untrue statement or alleged untrue statement of a material fact contained in the registration statement for the registration of the Securities as originally filed or in any amendment thereof, or in any Preliminary Prospectus or the Prospectus, or in any amendment thereof or supplement thereto, or arise out of or are based upon the omission or alleged omission to state therein a material fact required to be stated therein or necessary to make the statements therein not misleading, and agrees to reimburse each such indemnified party, as incurred, for any legal or other expenses reasonably incurred by them in connection with investigating or defending any such loss, claim, damage, liability or action; provided, however, that the Company will not be liable in any such case to the extent that any such loss, claim, damage or liability arises out of or is based upon any such

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untrue statement or alleged untrue statement or omission or alleged omission made therein in reliance upon and in conformity with written information furnished to the Company by or on behalf of any Underwriter through the Representatives specifically for inclusion therein. This indemnity agreement will be in addition to any liability which the Company may otherwise have.

        (b)   Each Underwriter severally and not jointly agrees to indemnify and hold harmless the Company, each of its directors, each of its officers who signs the Registration Statement, and each person who controls the Company within the meaning of either the Act or the Exchange Act to the same extent as the foregoing indemnity from the Company to each Underwriter, but only with reference to written information relating to such Underwriter furnished to the Company by or on behalf of such Underwriter through the Representatives specifically for inclusion in the documents referred to in the foregoing indemnity. This indemnity agreement will be in addition to any liability which any Underwriter may otherwise have. The Company acknowledges that the statements set forth in the last paragraph of the cover page regarding delivery of the Securities and, under the heading "Underwriting", (i) the list of underwriters and their respective participation in the sale of the Securities, (ii) the third paragraph, (iii) the sixth paragraph, (iv) the ninth paragraph and (v) the tenth paragraph in any Preliminary Prospectus and the Prospectus constitute the only information furnished in writing by or on behalf of the several Underwriters for inclusion in any Preliminary Prospectus or the Prospectus.

        (c)   Promptly after receipt by an indemnified party under this Section 8 of notice of the commencement of any action, such indemnified party will, if a claim in respect thereof is to be made against the indemnifying party under this Section 8, notify the indemnifying party in writing of the commencement thereof; but the failure so to notify the indemnifying party (i) will not relieve it from liability under paragraph (a) or (b) above unless and to the extent it did not otherwise learn of such action and such failure results in the forfeiture by the indemnifying party of substantial rights and defenses and (ii) will not, in any event, relieve the indemnifying party from any obligations to any indemnified party other than the indemnification obligation provided in paragraph (a) or (b) above. The indemnifying party shall be entitled to appoint counsel of the indemnifying party's choice at the indemnifying party's expense to represent the indemnified party in any action for which indemnification is sought (in which case the indemnifying party shall not thereafter be responsible for the fees and expenses of any separate counsel retained by the indemnified party or parties except as set forth below); provided, however, that such counsel shall be reasonably satisfactory to the indemnified party. Notwithstanding the indemnifying party's election to appoint counsel to represent the indemnified party in an action, the indemnified party shall have the right to employ separate counsel (including local counsel), and the indemnifying party shall bear the reasonable fees, costs and expenses of such separate counsel if (i) the use of counsel chosen by the indemnifying party to represent the indemnified party would present such counsel with a conflict of interest, (ii) the actual or potential defendants in, or targets of, any such action include both the indemnified party and the indemnifying party and the indemnified party shall have reasonably concluded that there may be legal defenses available to it and/or other indemnified parties which are different from or additional to those available to the indemnifying party, (iii) the indemnifying party shall not have employed counsel reasonably satisfactory to the indemnified party to represent the indemnified party within a reasonable time after notice of the institution of such action or (iv) the indemnifying party shall authorize the indemnified party to employ separate counsel at the expense of the indemnifying party. An indemnifying party will not, without the prior written consent of the indemnified parties, settle or compromise or consent to the entry of any judgment with respect to any pending or threatened claim, action, suit or proceeding in respect of which indemnification or contribution may be sought hereunder (whether or not the indemnified parties are actual or potential parties to such claim or action) unless such settlement, compromise or consent includes an unconditional release of each indemnified party from all liability arising out of such claim, action, suit or proceeding.

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        (d)   In the event that the indemnity provided in paragraph (a) or (b) of this Section 8 is unavailable to or insufficient to hold harmless an indemnified party for any reason, the Company and the Underwriters severally agree to contribute to the aggregate losses, claims, damages and liabilities (including legal or other expenses reasonably incurred in connection with investigating or defending same) (collectively "Losses") to which the Company and one or more of the Underwriters may be subject in such proportion as is appropriate to reflect the relative benefits received by the Company on the one hand and by the Underwriters on the other from the offering of the Securities; provided, however, that in no case shall any Underwriter (except as may be provided in any agreement among underwriters relating to the offering of the Securities) be responsible for any amount in excess of the underwriting discount or commission applicable to the Securities purchased by such Underwriter hereunder. If the allocation provided by the immediately preceding sentence is unavailable for any reason, the Company and the Underwriters severally shall contribute in such proportion as is appropriate to reflect not only such relative benefits but also the relative fault of the Company on the one hand and of the Underwriters on the other in connection with the statements or omissions which resulted in such Losses as well as any other relevant equitable considerations. Benefits received by the Company shall be deemed to be equal to the total net proceeds from the offering (before deducting expenses) received by it, and benefits received by the Underwriters shall be deemed to be equal to the total underwriting discounts and commissions, in each case as set forth on the cover page of the Prospectus. Relative fault shall be determined by reference to, among other things, whether any untrue or any alleged untrue statement of a material fact or the omission or alleged omission to state a material fact relates to information provided by the Company on the one hand or the Underwriters on the other, the intent of the parties and their relative knowledge, access to information and opportunity to correct or prevent such untrue statement or omission. The Company and the Underwriters agree that it would not be just and equitable if contribution were determined by pro rata allocation or any other method of allocation which does not take account of the equitable considerations referred to above. Notwithstanding the provisions of this paragraph (d), no person guilty of fraudulent misrepresentation (within the meaning of Section 11(f) of the Act) shall be entitled to contribution from any person who was not guilty of such fraudulent misrepresentation. For purposes of this Section 8, each person who controls an Underwriter within the meaning of either the Act or the Exchange Act and each director, officer, employee and agent of an Underwriter shall have the same rights to contribution as such Underwriter, and each person who controls the Company within the meaning of either the Act or the Exchange Act, each officer of the Company who shall have signed the Registration Statement and each director of the Company shall have the same rights to contribution as the Company, subject in each case to the applicable terms and conditions of this paragraph (e).

        9.    Default by an Underwriter.    If any one or more Underwriters shall fail to purchase and pay for any of the Securities agreed to be purchased by such Underwriter or Underwriters hereunder and such failure to purchase shall constitute a default in the performance of its or their obligations under this Agreement, the remaining Underwriters shall be obligated severally to take up and pay for (in the respective proportions which the amount of Securities set forth opposite their names in Schedule I hereto bears to the aggregate amount of Securities set forth opposite the names of all the remaining Underwriters) the Securities which the defaulting Underwriter or Underwriters agreed but failed to purchase; provided, however, that in the event that the aggregate amount of Securities which the defaulting Underwriter or Underwriters agreed but failed to purchase shall exceed 10% of the aggregate amount of Securities set forth in Schedule I hereto, the remaining Underwriters shall have the right to purchase all, but shall not be under any obligation to purchase any, of the Securities, and if such nondefaulting Underwriters do not purchase all the Securities, this Agreement will terminate without liability to any nondefaulting Underwriter or the Company. In the event of a default by any Underwriter as set forth in this Section 9, the Closing Date shall be postponed for such period, not exceeding five Business Days, as the Representatives shall determine in order that the required changes in the Registration Statement and the Prospectus or in any other documents or arrangements may be

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effected. Nothing contained in this Agreement shall relieve any defaulting Underwriter of its liability, if any, to the Company and any nondefaulting Underwriter for damages occasioned by its default hereunder.

        10.    Termination.    This Agreement shall be subject to termination in the absolute discretion of the Representatives, by notice given to the Company prior to delivery of and payment for the Securities, if at any time prior to such time (i) trading in the Company's Common Stock shall have been suspended by the Commission or the New York Stock Exchange or trading in securities generally on the New York Stock Exchange shall have been suspended or limited or minimum prices shall have been established on such exchange, (ii) a banking moratorium shall have been declared either by Federal or New York State authorities or (iii) there shall have occurred any outbreak or escalation of hostilities, declaration by the United States of a national emergency or war, or other calamity or crisis the effect of which on financial markets is such as to make it, in the sole judgment of the Representatives, impractical or inadvisable to proceed with the offering or delivery of the Securities as contemplated by the Prospectus (exclusive of any supplement thereto).

        11.    Representations and Indemnities to Survive.    The respective agreements, representations, warranties, indemnities and other statements of the Company or its officers and of the Underwriters set forth in or made pursuant to this Agreement will remain in full force and effect, regardless of any investigation made by or on behalf of any Underwriter or the Company or any of the officers, directors, employees, agents or controlling persons referred to in Section 8 hereof, and will survive delivery of and payment for the Securities. The provisions of Sections 7 and 8 hereof shall survive the termination or cancellation of this Agreement.

        12.    Notices.    All communications hereunder will be in writing and effective only on receipt, and, if sent to the Representatives, will be mailed, delivered or telefaxed to Citigroup Global Markets, Inc.; or, if sent to the Company, will be mailed, delivered or telefaxed to (801) 584-5788 and confirmed to it at 500 Huntsman Way, Salt Lake City, Utah 84108, attention of the Legal Department.

        13.    Successors.    This Agreement will inure to the benefit of and be binding upon the parties hereto and their respective successors and the officers, directors, employees, agents and controlling persons referred to in Section 8 hereof, and no other person will have any right or obligation hereunder.

        14.    Applicable Law.    This Agreement will be governed by and construed in accordance with the laws of the State of New York applicable to contracts made and to be performed within the State of New York.

        15.    Counterparts.    This Agreement may be signed in one or more counterparts, each of which shall constitute an original and all of which together shall constitute one and the same agreement.

        16.    Headings.    The section headings used herein are for convenience only and shall not affect the construction hereof.

        17.    Definitions.    The terms which follow, when used in this Agreement, shall have the meanings indicated.

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        If the foregoing is in accordance with your understanding of our agreement, please sign and return to us the enclosed duplicate hereof, whereupon this letter and your acceptance shall represent a binding agreement among the Company and the several Underwriters.

    Very truly yours,

 

 

Huntsman Corporation

 

 

By:

 


Name:
Title:

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        The foregoing Agreement is hereby confirmed and accepted as of the date first above written.

Citigroup Global Markets Inc.    

By:

 


Name:
Title:

 

 

Credit Suisse First Boston LLC

 

 

By:

 


Name:
Title:

 

 

Deutsche Bank Securities Inc.

 

 

By:

 


Name:
Title:

 

 

By:

 

 

 

 
   
Name:
Title:
   

Merrill Lynch, Pierce Fenner & Smith Incorporated

 

 

By:

 

 

 

 
   
Name:
Title:
   

        For themselves and the other several Underwriters named in Schedule I to the foregoing Agreement.

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SCHEDULE I

Underwriters

  Number of Underwritten
Securities to be Purchased

Citigroup Global Markets Inc.    
Credit Suisse First Boston LLC    
Deutsche Bank Securities Inc.    
Merrill Lynch, Pierce, Fenner & Smith Incorporated    
J.P. Morgan Securities Inc.    
Lehman Brothers Inc.    
UBS Securities LLC    
CIBC World Markets Corp.    
Jeffries & Company, Inc.    
Natexis Bleichroeder, Inc.    
WR Hambrecht & Co, LLC    
Scotia Capital (USA) Inc.    
Total    

SCHEDULE II

Reorganization Agreements


SCHEDULE III

Scheduled Subsidiaries

Alta One Inc.
HMP Equity Holdings Corporation
Huntsman Advanced Materials Investment LLC
Huntsman Advanced Materials Holdings LLC
Huntsman Advanced Materials LLC
Huntsman Group Inc.
Huntsman Holdings, LLC
Huntsman Holdings Preferred Member, LLC
Huntsman International Holdings LLC
Huntsman International LLC
Huntsman LLC
Huntsman Specialty Chemicals Holdings Corp.
Huntsman Specialty Chemicals Corp.


SCHEDULE IV

Foreign Qualifications

Entity

  Jurisdiction(s) of Foreign
Qualification

  Status
Huntsman Corporation        
Huntsman Holdings, LLC        
Alta One Inc.        
HMP Equity Holdings Corporation        
Huntsman Advance Materials Holdings LLC        
Huntsman Advanced Materials LLC        
Huntsman Group Inc.        
Huntsman Holdings Preferred Member, LLC        
Huntsman International Holdings LLC        
Huntsman International LLC        
Huntsman LLC        
Huntsman Specialty Chemicals Holdings Corp.        
Huntsman Specialty Chemicals Corp.        


ANNEX A

Form of Certificate of Designations



ANNEX B


Form of Letter from Deloitte & Touche LLC



ANNEX C


Form of CFO/Controller Certificate




QuickLinks

SCHEDULE I
Form of Certificate of Designations
Form of Letter from Deloitte & Touche LLC
Form of CFO/Controller Certificate