Document:

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                                                                     EXHIBIT 4.1

                                                                       EXHIBIT A
                                                                   TO SECURITIES
                                                              PURCHASE AGREEMENT

                                 FORM OF WARRANT

THE SECURITIES REPRESENTED BY THIS CERTIFICATE HAVE BEEN ACQUIRED SOLELY FOR
INVESTMENT AND HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS
AMENDED, OR ANY STATE SECURITIES LAWS. SUCH SECURITIES MAY NOT BE SOLD OR
TRANSFERRED IN THE ABSENCE OF SUCH REGISTRATION OR AN OPINION OF COUNSEL FOR THE
HOLDER, REASONABLY SATISFACTORY TO THE COMPANY, THAT SUCH REGISTRATION IS NOT
REQUIRED

THE SECURITIES REPRESENTED BY THIS CERTIFICATE ARE SUBJECT TO THE RESTRICTIONS
ON TRANSFER SET FORTH IN A STOCKHOLDERS AGREEMENT. NO TRANSFER OF THE SECURITIES
REPRESENTED BY THIS CERTIFICATE SHALL BE EFFECTIVE UNLESS AND UNTIL THE TERMS
AND CONDITIONS OF SUCH STOCKHOLDERS AGREEMENT HAVE BEEN COMPLIED WITH IN FULL
AND NO PERSON MAY REQUEST THE COMPANY TO RECORD THE TRANSFER OF ANY SUCH
SECURITIES IF SUCH TRANSFER IS IN VIOLATION OF SUCH STOCKHOLDERS AGREEMENT. A
COPY OF SUCH STOCKHOLDERS AGREEMENT MAY BE OBTAINED AT NO COST BY WRITTEN
REQUEST MADE BY THE HOLDER OF RECORD OF THIS CERTIFICATE TO THE SECRETARY OF THE
COMPANY AT THE PRINCIPAL EXECUTIVE OFFICES OF THE COMPANY.

                            LYONDELL CHEMICAL COMPANY

               WARRANT FOR THE PURCHASE OF SHARES OF COMMON STOCK,
                            PAR VALUE $1.00 PER SHARE

                             Issued _________, 2002

                             (Subject to Adjustment)

No. [___]                                                       5,000,000 Shares

     THIS CERTIFIES THAT, for value received, Occidental Chemical Holding
Corporation, a California corporation, the registered holder hereof (the
"Holder"), is entitled to subscribe for and purchase from LYONDELL CHEMICAL
COMPANY, a Delaware corporation (the "Company"), upon the terms and conditions
set forth herein, at any time or from time to time, during the Exercise Period,
5 million fully paid and nonassessable shares of Original Common Stock (each
share, a "Warrant Share") of the Company, at the Exercise Price, as such number
of shares and Exercise Price may be adjusted pursuant to Section 4. This Warrant
is the warrant issued pursuant to the Securities Purchase Agreement.

     This Warrant is being executed contemporaneously with the Stockholder
Agreement. Neither this Warrant, the Warrant Shares nor the Net Payment Shares
may be sold or transferred except in accordance with the legend above and the
terms and provisions of the Stockholder Agreement.

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     1.   Certain Definitions.

     As used in this Warrant, the following terms shall have the following
respective meanings:

     "15-Day Price" shall have the meaning set forth in Section 4(a).

     "Agent" shall have the meaning set forth in Section 12(m).

     "Aggregate Exercise Price" shall mean (i) if the Company does not elect to
exercise its Net Payment Right, an amount equal to the Exercise Price multiplied
by the number of Warrant Shares for which this Warrant is being exercised or
(ii) if the Company elects to exercise its Net Payment Right as to a portion of
the Warrant exercised, an amount equal to (x) the Exercise Price multiplied by
(y) the number of Warrant Shares for which this Warrant is being exercised minus
the number of Warrant Shares for which the Company exercises its Net Payment
Right.

     "Business Day" shall mean any day on which the NYSE is open for trading.

     "Company" shall mean Lyondell Chemical Company, a Delaware corporation, or
any Surviving Entity (as defined in the Stockholder Agreement).

     "Company Election Notice" shall have the meaning set forth in Section 2(a).

     "Corporate Change" shall have the meaning set forth in Section 4(d).

     "Daily Price" shall mean, on any day, the average (calculated to the
nearest thousandth) of the high and low per share sales prices of Original
Common Stock on such day for sales conducted regular way on the NYSE (as
reported on www.nysenet.com or, if not reported thereby, another authoritative
source).

     "Exercise Date" shall mean any date on which the Holder delivers an
Exercise Notice to the Company.

     "Exercise Notice" shall mean an exercise notice substantially in the form
attached hereto as Exhibit A.

     "Exercise Period" shall mean the period commencing the Issue Date and
ending at 5:00 p.m., Houston, Texas time, on the fifth anniversary thereof.

     "Exercise Price" shall mean $25 per Warrant Share, as adjusted pursuant to
Section 4.

     "Holder" shall mean Occidental Chemical Holding Corporation, a California
corporation, and shall include its permitted successors and assigns.

     "Issue Date" shall mean ______________, 2002.

     "Net Payment" shall mean an amount equal to (x) the excess, if any, of the
Daily Price on the Exercise Date to which the Net Payment relates over the
Exercise Price as of such Exercise

                                       -2-

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Date, multiplied by (y) the number of Warrant Shares for which the Company
exercises its Net Payment Right.

     "Net Payment Right" shall have the meaning set forth in Section 2(b).

     "Net Payment Shares" shall have the meaning set forth in Section 2(b).

     "Notice" shall have the meaning set forth in Section 12(d).

     "NYSE" shall mean the New York Stock Exchange, Inc.

     "Occidental" shall mean Occidental Petroleum Corporation, a Delaware
corporation.

     "Original Common Stock" shall mean shares of the series of common stock,
$1.00 par value per share, of the Company in existence on the date hereof that
is not Series B Common Stock.

     "Person" shall mean any natural person, corporation, partnership, limited
liability company, joint venture, association, trust or other entity or
organization.

     "PIK Dividend," with respect to the Series B Common Stock, shall have the
meaning set forth in the Amended and Restated Certificate of Incorporation of
Lyondell Chemical Company that was filed with the Secretary of State of the
State of Delaware on ______________, 2002.

     "Registration Rights Agreement" shall mean the Registration Rights
Agreement dated as of the Issue Date among the Company and the Holder.

     "Related Securities Agreements" shall mean the Stockholder Agreement, the
Securities Purchase Agreement and the Registration Rights Agreement.

     "Securities Purchase Agreement" shall mean that certain Securities Purchase
Agreement, dated July 8, 2002, by and between the Company and Occidental
Chemical Holding Corporation.

     "Series B Common Stock" shall mean shares of Series B Common Stock, $1.00
par value per share, of the Company.

     "Stockholder Agreement" shall mean that certain Stockholders Agreement
dated as of the Issue Date by and among the Company and the Stockholders (as
defined therein).

     "Subsidiary" shall mean, with respect to a Holder, any Person of which such
Holder, either directly or indirectly, owns 50% or more of the equity or voting
interests.

     "Transfer" shall have the meaning set forth in the Stockholder Agreement.

     "Transfer Notice and Adoption Agreement" shall mean a transfer notice and
adoption agreement substantially in the form attached hereto as Exhibit B.

     "Warrant" shall mean and include this Warrant and any Warrant or Warrants
hereafter issued as a consequence of exercise or Transfer of this Warrant in
whole or in part.

                                       -3-

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     "Warrant Share" shall have the meaning set forth in the first paragraph
hereof.

     "Wholly Owned Affiliate," with respect to any party, shall mean any
Affiliate of such party that is wholly owned, directly or indirectly, by such
party's ultimate parent entity.

     2.   Method of Exercise; Company's Net Payment Option; Certificates and New
Warrant.

          (a)   Exercise. Subject to compliance with applicable securities laws,
this Warrant may be exercised during the Exercise Period, in whole or in part,
by delivering a signed and completed Exercise Notice. Within two Business Days
after receiving a signed and completed Exercise Notice, the Company shall notify
the Holder of whether it will issue Warrant Shares or make a Net Payment in lieu
of issuing Warrant Shares for all or any portion of the Warrant exercised (the
"Company Election Notice"); provided, however, that if the Company does not
deliver a Company Election Notice within such two Business Day period, the
Company shall be required to (i) exercise its Net Payment Right with respect to
all of the Warrant Shares covered by the applicable Exercise Notice and (ii)
satisfy such Net Payment with cash. If the Company elects to exercise its Net
Payment Right, the Company Election Notice shall state the number of Warrant
Shares to which such Net Payment Right will apply and the form of such Net
Payment. Within three Business Days after delivery of a Company Election Notice
(or, if the Company does not deliver a Company Election Notice, within five
Business Days after delivery of an Exercise Notice), the Holder shall complete
its exercise of this Warrant by surrender of this Warrant to the Company at its
principal office, or at such other place designated by the Company, together
with the Aggregate Exercise Price, if applicable, paid by wire transfer of
immediately available funds to an account designated by the Company.

          (b)   Company's Net Payment Right. In lieu of delivering to the Holder
upon exercise of this Warrant all or any portion of the Warrant Shares, the
Company shall have the right in its sole discretion to make a Net Payment to the
Holder in the form of (i) cash, (ii) shares of Original Common Stock, (iii)
shares of Series B Common Stock (but only until the later of (x) the third
anniversary of the Issue Date or (y) the date the Holder or its Wholly Owned
Affiliate no longer beneficially owns shares of Series B Common Stock) or (iv) a
combination of (i), (ii) and (iii) (the "Net Payment Right"). If the Company
elects in its Company Election Notice to exercise its Net Payment Right by
delivering to the Holder the amount of all or any portion of the Net Payment in
shares of Original Common Stock or Series B Common Stock (each such share a "Net
Payment Share"), each such share shall be valued at the Daily Price on the
Exercise Date to which the Net Payment relates.

          (c)   Stock Certificates, Cash Payments and New Warrant. Within five
Business Days after the Holder completes its exercise of this Warrant in
accordance with Section 2(a), the Company shall issue and cause to be delivered
to or upon the written order of the exercising Holder and in the name of the
exercising Holder, (i) a certificate or certificates for the Warrant Shares
purchased and/or (ii) if the Company elected in the applicable Company Election
Notice to exercise its Net Payment Right as to all or any portion of the Warrant
Shares by issuance and delivery of Net Payment Shares, a certificate or
certificates representing such Net Payment Shares. If the Company (x) did not
deliver a Company Election Notice or (y) elected in a Company Election Notice to
exercise its Net Payment Right as to all or any portion of the

                                       -4-

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Warrant Shares in the form of cash, then the Company shall deliver the
applicable cash payment within three Business Days after the Holder completes
its exercise of this Warrant in accordance with Section 2(a) by wire transfer of
immediately available funds to an account designated by the Holder. If this
Warrant should be exercised in part only, the Company shall, within five
Business Days after completion of the exercise as set forth in Section 2(a),
execute and deliver a new Warrant evidencing the right of the Holder to purchase
the balance of the Warrant Shares (or portions thereof) subject to purchase
hereunder.

     3.   Stock Fully Paid; Reservation of Shares. Each Warrant Share issuable
upon exercise of this Warrant, upon receipt by the Company of the Exercise Price
therefore, and each Net Payment Share issuable upon exercise of this Warrant in
lieu of Warrant Shares, shall be validly issued, fully paid and nonassessable,
and free from all taxes, liens, and charges with respect to its issuance. So
long as this Warrant remains outstanding, the Company shall at all times reserve
and keep available out of its authorized and unissued Original Common Stock
solely for the purpose of providing for the exercise of the rights to purchase
all Warrant Shares granted pursuant to this Warrant such number of shares of
Original Common Stock as shall, from time to time, be sufficient therefor.

     4.   Adjustments. The number and kind of securities purchasable upon the
exercise of this Warrant and the Exercise Price shall be subject to adjustment
from time to time upon the occurrence of certain events, as follows:

          (a)   Daily Price Shortfall. If the average (rounded to the nearest
thousandth) of the Daily Prices for the 15 consecutive Business Days ending
December 31, 2002 (the "15-Day Price") is:

                (i)   less than or equal to $7.00 per share, then (A) the number
     of Warrant Shares purchasable upon this Warrant's exercise shall be
     increased to 6 million shares and (B) the Exercise Price shall be decreased
     to $22.30 per share;

                (ii)  greater than $7.00 per share and less than $11.00 per
     share, then (A) the number of Warrant Shares purchasable upon this
     Warrant's exercise shall be

                      5 million + (($11.00 - 15-Day Price) x 250,000);

     and (B) the Exercise Price shall be

                      $25 - (($11.00 - 15-Day Price) x $.675).

          (b)   Reclassification. If there is any reclassification or change in
the Company's Original Common Stock, the Company shall execute a new Warrant
providing that the Holder has the right to exercise such new Warrant and receive
upon such exercise (and payment of the same Exercise Price), in lieu of the
Warrant Shares previously issuable upon exercise of this Warrant, the kind and
amount of shares of stock, other securities, money, and property that a Holder
of an equivalent number of Warrant Shares would receive upon such
reclassification or change. Any such new Warrant shall provide for adjustments
that are as nearly equivalent as practicable to the adjustments provided for in
this Section 4, which shall apply similarly to successive reclassifications or
changes and to the Net Payment Right.

                                       -5-

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         (c) Stock Splits, Dividends and Combinations. If the Company at any
time subdivides its outstanding Original Common Stock or issues a stock dividend
on shares of Original Common Stock, the number of Warrant Shares purchasable
upon this Warrant's exercise immediately before such subdivision or stock
dividend shall be proportionately increased, and the Exercise Price shall be
proportionately decreased. If the Company at any time combines its outstanding
Original Common Stock, the number of Warrant Shares issuable upon this Warrant's
exercise immediately before such combination shall be proportionately decreased,
and the Exercise Price shall be proportionately increased. Any adjustment made
pursuant to this Section 4(c) shall become effective immediately after the
effective date of such event retroactive to the record date, if any, for such
event.

         (d) Consolidation, Merger, or Sale. If the Company consolidates or
merges with another entity (other than a consolidation or merger in which the
Company is the surviving or continuing entity and that does not result in any
change in the Original Common Stock), or Transfers or disposes of all or
substantially all of its assets to another entity (collectively, a "Corporate
Change"), then the Holder shall, upon exercising this Warrant, have the right to
receive the number of Warrant Shares, other Company securities or property, or
successor entity's securities or property, as the case may be, that the Holder
would have received upon such Corporate Change if the Holder had exercised this
Warrant immediately before such Corporate Change. If there is a Corporate
Change, the Company or its successor following such Corporate Change shall make
appropriate adjustments to the provisions of this Warrant (including those
relating to adjusting the Exercise Price, the number of Warrant Shares issuable
upon exercising this Warrant and the Company's Net Payment Right) so that this
Warrant will apply, as nearly as possible, to any shares or other property
deliverable upon exercise of this Warrant as if the Holder had exercised this
Warrant immediately before such Corporate Change and the Holder had carried out
the terms of the exchange such Corporate Change provided for effective as of the
consummation of such Corporate Change. The Company shall not effect any
Corporate Change unless, upon or before it is consummated, the Company's
successor following such Corporate Change has assumed in writing (x) the
obligation to deliver to the Holder the shares of stock or other securities,
cash or property that the Holder has the right to purchase in accordance with
this Section 4(d) and (y) the Company's other obligations under this Warrant.

         (e) Limitation on Adjustments. No adjustment in the number of Warrant
Shares purchasable upon exercise of this Warrant shall be required unless such
adjustment would require an increase or decrease of at least three percent in
the number of Warrant Shares then purchasable upon the exercise of this Warrant
or, if this Warrant is not then exercisable, the number of Warrant Shares
purchasable upon the exercise of this Warrant on the first date thereafter that
this Warrant become exercisable. No adjustment in the Exercise Price shall be
required if such adjustment is less than $.01. Any adjustments which by reason
of this Section 4(e) are not required to be made immediately shall be carried
forward and taken into account in any subsequent adjustment. All calculations
under this Section 4(e) shall be made to the nearest cent or to the nearest
one-thousandth of a share, as the case may be.

     5.  Notice of Adjustments and Corporate Change. Whenever the number of
Warrant Shares purchasable under this Warrant or the Exercise Price are adjusted
pursuant to Section 4, the Company shall promptly notify the Holder describing,
in reasonable detail, the event requiring the adjustment, the amount of the
adjustment, the method by which the

                                       -6-

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adjustment was calculated, the number and class of Warrant Shares that the
Holder has the right to purchase, and the Exercise Price for each Warrant Share
after effecting the adjustment. Failure to mail the notice or any defect therein
shall not affect the validity of the transaction requiring the mailing of such
notice.

         6.  Fractional Shares. The Holder does not have the right to exercise
this Warrant for fractional shares. In lieu of fractional shares, the Company
shall make a cash payment equal to the value of such fractional shares based on
the Exercise Price then in effect.

         7.  Securities Laws. In order to exercise this Warrant, the exercising
Holder shall, as a condition to such exercise, be required to make the
representations and warranties set forth in the Exercise Notice as of the date
of each such Exercise Notice. Each Holder agrees that all the provisions of the
Stockholder Agreement, if applicable and still in effect pursuant to the terms
thereof, shall apply to Warrant Shares and/or Net Payment Shares.

         8.  Mutilated or Missing Warrants. In case a certificate or
certificates evidencing this Warrant shall be mutilated, lost, stolen or
destroyed, the Company shall, at the request of a Holder, issue and deliver in
exchange and substitution for and upon cancellation of the mutilated certificate
or certificates, or in lieu of and substitution for the certificate or
certificates lost, stolen or destroyed, a new Warrant certificate or
certificates of like tenor and representing an equivalent right or interest, but
only upon receipt of evidence satisfactory to the Company of such loss, theft or
destruction of such Warrant and a bond of indemnity, if requested, also
satisfactory in form and amount at the Holder's cost. The Holder shall also
comply with such other reasonable regulations and pay such other reasonable
charges as the Company may prescribe in connection with the issuance and
delivery of a new Warrant certificate or certificates.

         9.  No Right as Stockholder. No Holder shall be entitled, in its
capacity as a Holder, to vote or receive dividends or be deemed the holder of
the Warrant Shares or Net Payment Shares, as applicable, or any other Company
securities that may at any time be issuable on this Warrant's exercise for any
purpose, nor shall anything contained in this Warrant be construed to confer
upon the Holder, in its capacity as a Holder, any of the rights of a Company
stockholder, including any right (i) to vote for the election of directors or
upon any matter submitted to stockholders at any stockholder meeting, (ii) to
give or withhold consent to any corporate action (whether upon any
recapitalization, issuance of stock, reclassification of stock, change of par
value, consolidation, merger, conveyance, or otherwise) or (iii) to receive
notice of meetings, to receive dividends or subscription rights, or otherwise,
until the Holder exercises this Warrant and the Warrant Shares or Net Payment
Shares, as applicable, issuable upon this Warrant's exercise have become
deliverable, as provided in this Warrant.

         10. Transfer of Warrant. Transfer of this Warrant and any Warrant
Shares and/or Net Payment Shares issued upon exercise of this Warrant is
restricted by Section 4 of the Stockholder Agreement. As a condition to the
Company's obligation to effect a Transfer permitted under Section 4 of the
Stockholder Agreement, any proposed transferee of this Warrant shall (i) be
required to demonstrate compliance with such article and (ii) agree in writing
with the Company to be bound by the terms of the Stockholder Agreement as if an
original signatory thereto by executing a Transfer Notice and Adoption
Agreement.

                                       -7-

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         11. Termination of Warrant. This Warrant, other than the rights and
obligations specified in this Section 11 and Sections 12(d), 12(m) and 12(n),
which survive termination of this Warrant, shall terminate and expire at 5:00
p.m., Houston, Texas time, on the last day of the Exercise Period.

         12. Miscellaneous.

             (a) Successors and Assigns. Except as may be expressly provided
herein, this Warrant shall be binding upon and inure to the benefit of the
successors of the Company and the Holder. Neither the Company nor the Holder may
otherwise assign or delegate any of its rights or obligations under this Warrant
without the prior written consent of the other, which consent shall be in the
sole and absolute discretion of the Company or the Holder, as applicable. Any
purported assignment or delegation without such consent shall be void and
ineffective.

             (b) Certain Events. The Holder agrees that this Warrant and the
obligations hereunder shall attach to this Warrant and the shares issued upon
exercise of this Warrant and shall be binding upon any Person to which legal or
beneficial ownership of such shares shall pass, whether by operation of law or
otherwise.

             (c) Benefits of Agreement Restricted to Parties. This Warrant is
made solely for the benefit of the Company and the Holder and no other Person
(including employees or shareholders of the Holder) shall have any right, claim
or cause of action under or by virtue of this Warrant.

             (d) Notices. All notices, requests and other communications
(collectively, the "Notices") made pursuant to this Warrant shall be in writing
and signed and correctly dated by the party sending such Notice. All Notices
shall be delivered personally (by courier or otherwise) or by facsimile to the
receiving party at the applicable address or facsimile number set forth below:

                                    If to the Company:

                                            Lyondell Chemical Company
                                            1221 McKinney Street, Suite 700
                                            Houston, Texas 77010
                                            Attention: Gerald A. O'Brien
                                            Facsimile: 713-309-2143

                                            with a copy to:

                                            Baker Botts L.L.P.
                                            910 Louisiana Street
                                            Houston, Texas 77002
                                            Attention: Stephen A. Massad
                                            Facsimile: 713-229-1522

                                       -8-

<PAGE>

                                        and

                                        Lyondell Chemical Company
                                        1221 McKinney Street, Suite 700
                                        Houston, Texas 77010
                                        Attention: General Counsel
                                        Facsimile: 713-309-7312

                               If to a Holder:

                                        Occidental Chemical Holding Corporation
                                        5005 LBJ Freeway
                                        Dallas, Texas 75244
                                        Attention: General Counsel
                                        Facsimile: 972-404-4155

Any Notice delivered personally shall be deemed to have been given on the date
it is so delivered, or upon attempted delivery if acceptance of delivery is
refused, and any Notice delivered by facsimile shall be deemed to have been
given on the first Business Day it is received by the addressee (or, if such
Notice is not received during regular business hours of a Business Day, at the
beginning of the next such Business Day). The address and facsimile numbers set
forth above may be changed by the Company or a Holder by giving Notice of such
change of address or facsimile number in the manner set forth in this Section
12(d).

             (e) Severability. In the event that any provision of this Warrant
shall finally be determined to be unlawful, such provision shall be deemed
severed from this Warrant and every other provision of this Warrant shall remain
in full force and effect.

             (f) Construction. In construing this Warrant, the following
principles shall be followed: (i) no consideration shall be given to the
captions of the sections, subsections or clauses, which are inserted for
convenience in locating the provisions of this Warrant and not as an aid in
construction; (ii) no consideration shall be given to the fact or presumption
that any of the Company or the Holder had a greater or lesser hand in drafting
this Warrant; (iii) the word "includes" and its syntactic variants mean
"includes, but is not limited to" and corresponding syntactic variant
expressions; (iv) the plural shall be deemed to include the singular, and vice
versa; (v) references in this Warrant to Sections and Exhibits shall be deemed
to be references to Sections of, and Exhibits to, this Warrant unless the
context shall otherwise require; (vi) all Exhibits attached to this Warrant
shall be deemed incorporated herein as if set forth in full herein; (vii) the
words "hereof", "herein" and "hereunder" and words of similar import shall refer
to this Warrant as a whole and not to any particular provision of this Warrant;
and (viii) unless otherwise expressly provided, any agreement, instrument or
statute defined or referred to herein means such agreement, instrument or
statute as from time to time amended, modified or supplemented, including (in
the case of agreements or instruments) by waiver or consent and (in the case of
statutes) by succession of comparable successor statutes and references to all
attachments thereto and instruments incorporated therein.

                                       -9-

<PAGE>

             (g) Entire Agreement. This Agreement together with the Related
Securities Agreements set forth the entire agreement and understanding among the
Company and the Holder as to the subject matter hereof and merges and supercedes
all prior discussions, agreements and understandings of every kind and nature
among them.

             (h) Counterparts. This Warrant may be executed in one or more
counterparts, each of which shall constitute an original, and all of which when
taken together shall constitute one and the same original document.

             (i) Governing Law. The laws of the State of Delaware shall govern
the construction, interpretation and effect of this Warrant without giving
effect to any conflicts of law principles.

             (j) Transaction Costs. The Company and the Holder shall each be
solely responsible for and bear all of its own respective costs, fees and
expenses.

             (k) Amendment. All waivers, modifications, amendments or
alterations of this Warrant shall require the written approval of the Company
and all Holders. Except as provided in the preceding sentence, no action taken
pursuant to this Warrant, including any investigation by or on behalf of the
Company or a Holder, shall be deemed to constitute a waiver by the party taking
such action of compliance with any representations, warranties, covenants or
agreements contained herein and/or in any documents delivered or to be delivered
pursuant to this Warrant. The waiver by the Company or a Holder of a breach of
any provision of this Warrant shall not operate or be construed as a waiver of
any subsequent breach.

             (l) Specific Performance. Each Holder and the Company agree that
each would be irreparably damaged if for any reason a party fails to perform any
of its obligations under this Warrant, and that a party would not have an
adequate remedy at law for money damages in such event. Accordingly, each other
party shall be entitled to seek specific performance and injunctive and other
equitable relief to enforce the performance of this Warrant by any other party.
This provision is without prejudice to any other rights that a party may have
against another party for any failure to perform its obligations under this
Warrant.

             (m) Jurisdiction; Consent to Service of Process; Waiver. ANY
JUDICIAL PROCEEDING BROUGHT AGAINST THE COMPANY OR THE HOLDER UNDER OR ARISING
OUT OF OR IN CONNECTION WITH THIS WARRANT SHALL BE BROUGHT IN THE FEDERAL OR
STATE COURTS OF THE STATE OF DELAWARE, AND, BY EXECUTION AND DELIVERY OF THIS
WARRANT, EACH OF THE COMPANY AND THE HOLDER ACCEPTS THE EXCLUSIVE JURISDICTION
OF SUCH COURTS AND IRREVOCABLY AGREES TO BE BOUND BY ANY JUDGMENT (AS FINALLY
ADJUDICATED) RENDERED THEREBY IN CONNECTION WITH THIS WARRANT. EACH OF THE
COMPANY AND THE HOLDER SHALL APPOINT THE CORPORATION TRUST COMPANY, THE
PRENTICE-HALL CORPORATION SYSTEM, INC. OR A SIMILAR ENTITY (THE "AGENT") AS
AGENT TO RECEIVE ON ITS BEHALF SERVICE OF PROCESS IN ANY PROCEEDING IN ANY SUCH
COURT IN THE STATE OF DELAWARE, AND EACH OF THE COMPANY AND THE HOLDER SHALL
MAINTAIN THE APPOINTMENT OF SUCH AGENT (OR A SUBSTITUTE AGENT) FROM THE DATE

                                       -10-

<PAGE>

HEREOF UNTIL THE EARLIER OF THE CLOSING DATE OR THE TERMINATION OF THIS WARRANT
AND SATISFACTION OF ALL OBLIGATIONS HEREUNDER. THE FOREGOING CONSENTS TO
JURISDICTION AND APPOINTMENTS OF AGENT TO RECEIVE SERVICE OF PROCESS SHALL NOT
CONSTITUTE GENERAL CONSENTS TO SERVICE OF PROCESS IN THE STATE OF DELAWARE FOR
ANY PURPOSE EXCEPT AS PROVIDED ABOVE AND SHALL NOT BE DEEMED TO CONFER RIGHTS ON
ANY PERSON OTHER THAN THE COMPANY AND THE HOLDER. EACH OF THE COMPANY AND THE
HOLDER HEREBY WAIVES ANY OBJECTION IT MAY HAVE BASED ON LACK OF PERSONAL
JURISDICTION, IMPROPER VENUE OR FORUM NON-CONVENIENS.

             (n) Waiver of Jury Trial. EACH OF THE COMPANY AND THE HOLDER HEREBY
KNOWINGLY AND INTENTIONALLY, IRREVOCABLY AND UNCONDITIONALLY WAIVES TRIAL BY
JURY IN ANY LEGAL ACTION OR PROCEEDING ARISING OUT OF OR IN CONNECTION WITH THIS
WARRANT AND FOR ANY COUNTERCLAIM THEREIN.

             (o) Further Assurances. From time to time, at the request of the
Company or a Holder, the parties shall execute and deliver or cause to be
executed and delivered such additional documents and instruments and take all
such further action as may be necessary or desirable to consummate the
transactions contemplated by this Warrant.

                                       -11-

<PAGE>

     IN WITNESS WHEREOF, the Company has caused this Warrant to be duly executed
by a duly authorized officer on the day and year first written below.

Dated: ____________, 2002.

                                                 LYONDELL CHEMICAL COMPANY

                                                 By: ___________________________
                                                     Name:
                                                     Title:

Holder:

OCCIDENTAL CHEMICAL HOLDING CORPORATION

By: ___________________________
    Name:
    Title:

<PAGE>

                                    EXHIBIT A

                                 EXERCISE NOTICE

                    (To be executed upon exercise of Warrant)

TO:  Lyondell Chemical Company
     1221 McKinney Street, Suite 700
     Houston, Texas 77010
     Attention: Gerald A. O'Brien
     Telecopy Number: 713-309-2143

     Capitalized terms used in this Exercise Notice but not defined herein have
the meanings set forth in the Warrant dated _______________, 2002 (the
"Warrant").

     1.   Election. The undersigned hereby irrevocably elects to purchase
__________ Warrant Shares pursuant to the terms of the Warrant and shall deliver
the Aggregate Exercise Price, if applicable, and the Warrant as provided in
Section 2(a) of the Warrant.

     2.   Representations and Warranties. The Holder hereby represents and
warrants to the Company that, as of the date of this Exercise Notice, with
respect to the exercise of the Warrant and the purchase of Warrant Shares and/or
Net Payment Shares, the following are true and correct:

          (a)  Investment. Holder acknowledges and agrees that all Warrant
     Shares and/or Net Payment Shares (collectively, the "Subject Securities")
     will be subject to the Stockholder Agreement and, among other things, will
     bear the legends specified therein. Holder is acquiring the Subject
     Securities for investment for its own account, not as a nominee or agent,
     and not with a view to, or for resale in connection with, any distribution
     thereof in violation of applicable law, and has not offered or sold any
     portion of the Subject Securities to be acquired by it. Holder acknowledges
     and understands that investment in the Subject Securities is subject to a
     high degree of risk and that it must bear the economic risk of its
     investment for an indefinite period of time because the Subject Securities
     must be held indefinitely (i) until subsequently registered under the
     Securities Act and applicable state and other securities laws or (ii)
     unless an exemption from registration is available which depends upon,
     among other things, the bona fide nature of Holder's investment intent and
     the accuracy of Holder's representations as expressed herein. Holder
     understands that any transfer agent of the Company will be issued stop
     transfer instructions with respect to the Subject Securities unless such
     transfer is subsequently registered under the Securities Act and applicable
     state and other securities laws or unless an exemption from such
     registration is available. Holder was not organized for the purpose of
     acquiring the Subject Securities.

          (b)  Investigation; No General Solicitation. Holder has received a
     copy of all forms, reports and documents that the Company is required to
     file with the Securities and Exchange Commission since December 31, 2001
     (the "Company SEC Reports"). Holder has had a reasonable opportunity to ask
     questions relating to and otherwise discuss the information set forth in
     the Company SEC Reports and the Company's business,

                                       A-1

<PAGE>

     management and financial affairs with the Company's management and other
     parties, and Holder has received satisfactory responses to its inquiries.
     To the extent necessary, Holder has retained, at the expense of Holder, and
     relied upon appropriate professional advice regarding the investment, tax
     and legal merits and consequences of its purchaser of the Subject
     Securities hereunder. Holder has relied only on its own independent
     investigation before deciding to acquire the Subject Securities.

          (c)  Sophistication and Financial Condition of Stockholder. Holder is
     an experienced and sophisticated investor and has such knowledge and
     experience in financial and business matters or its professional advisors
     have such knowledge and experience in financial and business matters as are
     necessary to evaluate the merits and risks of an investment in the Subject
     Securities and to evaluate the merits and risks of its investment and
     protect its own interest in connection with the acquisition of a Subject
     Security. Holder is able to bear the economic risk of this investment
     regarding the Company, is able to hold the Subject Securities indefinitely
     and has a sufficient net worth to sustain a loss of its entire investment
     in the Company in the event such loss should occur.

          (d)  Status of the Company Securities. Holder has been informed by the
     Company that the Subject Securities have not been and will not be
     registered under the Securities Act or under any state securities laws,
     including Section 25102(f) of the California Corporations Code, except as
     specifically provided in the Registration Rights Agreement, and are being
     offered and sold in reliance upon federal and state exemptions for
     transactions not involving any public offering.

     3.   Delivery of Certificates and Cash. As provided in Section 2 of the
Warrant, upon receipt of the Aggregate Purchase Price, if applicable, and the
Warrant, please issue in the name of the undersigned (i) a certificate or
certificates representing the applicable number of Warrant Shares and/or (ii) if
the Company elects to exercise its Net Payment Right by issuing Net Payment
Shares, a certificate or certificates representing such Net Payment Shares. If
the Company elects to exercise its Net Payment Right by delivery of cash, please
wire transfer immediately available funds to the account designated below. Cash
in lieu of any fractional shares should also be sent by wire transfer of
immediately available funds to the account designated below.

                            ________________________
                                     (Name)

                            ________________________

                            ________________________
                                    (Address)

                            ________________________
                                    (Account)

                                       A-2

<PAGE>

                                      __________________________________________
                                                      (Signature)
                                      Name: ____________________________________
                                      Title: ___________________________________
_______________________________
          (Date)

Note: The above signature must correspond exactly with the name on the first
      page of this Warrant or with the name of the Transferee appearing the
      Transfer form below.

If the number of Warrant Shares the Holder elects to purchase hereunder shall
not be all the shares purchasable under the Warrant, a new Warrant is to be
issued in the name of the registered Holder for the balance remaining of the
Warrant Shares purchasable thereunder.

                                       A-3

<PAGE>

                                    EXHIBIT B

                 FORM OF TRANSFER NOTICE AND ADOPTION AGREEMENT

(To be executed by the registered Holder and the Transferee if such Holder
desires to Transfer the attached Warrant and such Transfer is permissible under
the terms of the Warrant attached hereto and the Stockholder Agreement.)

     This Transfer Notice ("Transfer Notice") is executed pursuant to the terms
and conditions of the Warrant (the "Warrant") dated ___________, 2002 to
purchase ________ shares of Original Common Stock, par value $1.00 per share, of
Lyondell Chemical Company, a Delaware corporation (the "Company"), by the Holder
executing this Transfer Notice (the "Transferor"). A copy of the Warrant is
attached hereto and incorporated herein by reference. Capitalized terms used in
this Transfer Notice but not defined herein have the meanings set forth in the
Warrant.

     1.1  Transfer. For value received, the Transferor hereby Transfers unto
_______________________________________________ (the "Transferee") the within
Warrant, together with all right, title and interest therein, and does hereby
irrevocably constitute and appoint ____________________ attorney to Transfer the
Warrant on the books of the Company, with full power of substitution. The number
of Warrant Shares Transferred pursuant to this Transfer Notice is
______________. If such number of Warrant Shares are not all of the Warrant
Shares represented by the Warrant, a new Warrant is to be issued in the name of
the Transferor for the balance of the remaining Warrant Shares.

     1.2  Acknowledgement. Transferee acknowledges that Transferee is acquiring
the Warrant subject to the terms and conditions of the Warrant and the
Stockholders Agreement dated ____________, 2002 among Company and the
Stockholders (as defined therein) (the "Stockholder Agreement"). Transferee
acknowledges that, during the term of the Stockholder Agreement, the Warrant is,
and any Warrant Shares and/or Net Payment Shares issued upon exercise thereof
will be, a Restricted Security (as defined in the Stockholder Agreement). A copy
of the Stockholder Agreement is attached hereto and incorporated herein by
reference.

     1.3  Agreement. Transferee (i) agrees that the Warrant and all Warrant
Shares and/or Net Payment Shares issued to Transferee and shares of Original
Common Stock that may be acquired by Transferee in the future, shall be bound by
and subject to the terms of the Stockholder Agreement pursuant to the terms
thereof and (ii) hereby adopts the Stockholder Agreement with the same force and
effect as if it were originally a party thereto and, effective as of the date
hereof, is a Stockholder as defined therein.

     1.4  Representation. Transferee is a wholly owned Subsidiary of the
Transferor. After giving effect to the Transfer hereunder, the Transferee owns
the total number of Warrants, shares of Original Common Stock and shares of
Series B Common Stock set forth next to its signature hereto.

                                       B-1

<PAGE>

     1.5  Notice. The address of the Transferee for purposes of Section 12(d) of
the Warrant is as follows:

                           ___________________________
                           ___________________________
                           ___________________________
                           ___________________________
                           Attention: ________________
                           Telecopy Number: __________

                           with a copy to:

                           ___________________________
                           ___________________________
                           ___________________________
                           ___________________________
                           Attention: ________________
                           Telecopy Number: __________

     Dated: ____________________

                                           [TRANSFEROR]

                                           By: _________________________________
                                           Name:
                                           Title:

                                           [TRANSFEREE]

                                           By: _________________________________
                                           Name:
                                           Title:
                                           Warrants: ___________________________
                                           Original Common Stock: ______________
                                           Series B Common Stock: ______________

Note: The above signature must correspond exactly with the name on the first
      page of the Warrant or with the name of the Transferee appearing in the
      Transfer Notice and Adoption Agreement attached hereto.

                                       B-2<PAGE>

                                                                     EXHIBIT 4.2

                                                                       EXHIBIT B
                                                                   TO SECURITIES
                                                              PURCHASE AGREEMENT

--------------------------------------------------------------------------------

                                     FORM OF

                             STOCKHOLDERS AGREEMENT

                                      AMONG

                           LYONDELL CHEMICAL COMPANY,

                                       AND

                                THE STOCKHOLDERS

                                AS DEFINED HEREIN

                                 ________, 2002

--------------------------------------------------------------------------------

<PAGE>

                                TABLE OF CONTENTS

<TABLE>
<CAPTION>
                                                                               Page
<S>                                                                               <C>
SECTION 1 TERM .................................................................  1
    1.1    Term ................................................................  1
    1.2    Effect of Termination ...............................................  1

SECTION 2 STANDSTILL ...........................................................  2
    2.1    Standstill ..........................................................  2
    2.2    Exceptions ..........................................................  3

SECTION 3 VOTING PROVISIONS; BOARD APPOINTMENTS; GOVERNANCE
            MATTERS ............................................................  4
    3.1    Voting Agreement ....................................................  4
    3.2    Proxies and Voting Agreements .......................................  4
    3.3    Board Appointments ..................................................  4
    3.4    Conversion of Shares of Series B Common Stock into Shares of Original
            Common Stock .......................................................  5
    3.5    Number of Authorized Shares of Series B Common Stock ................  6

SECTION 4 TRANSFERS ............................................................  6
    4.1    Transfers ...........................................................  6
    4.2    Compliance Certificate; Adoption Agreement ..........................  7
    4.3    Invalid Transfers ...................................................  7
    4.4    Compliance with Securities Laws .....................................  8
    4.5    Restrictive Legends .................................................  8

SECTION 5 REGISTRATION RIGHTS; ADJUSTMENTS ..................................... 10
    5.1    Registration Rights ................................................. 10
    5.2    Adjustments ......................................................... 10

SECTION 6 REPRESENTATIONS AND WARRANTIES OF THE STOCKHOLDERS ................... 11
    6.1    Organization. ....................................................... 11
    6.2    Corporate Power and Authority ....................................... 11
    6.3    Binding Effect ...................................................... 11
    6.4    Ownership ........................................................... 11
    6.5    Total Shares ........................................................ 11
    6.6    Finder's Fees ....................................................... 12
    6.7    Investment .......................................................... 12
    6.8    Investigation; No General Solicitation .............................. 12
    6.9    Sophistication and Financial Condition of Stockholder ............... 12
    6.10   Status of Subject Securities ........................................ 13
    6.11   Government Consent .................................................. 13

SECTION 7 MISCELLANEOUS ........................................................ 13
    7.1    Successors and Assigns .............................................. 13
</TABLE>

                                      -i-

<PAGE>

<TABLE>
<S>                                                                           <C>
    7.2    Certain Events ................................................... 13
    7.3    Benefits of Agreement Restricted to Parties ...................... 13
    7.4    Notices .......................................................... 13
    7.5    Severability ..................................................... 14
    7.6    Construction ..................................................... 15
    7.7    Entire Agreement ................................................. 15
    7.8    Counterparts ..................................................... 15
    7.9    Governing Law .................................................... 15
    7.10   Transaction Costs ................................................ 15
    7.11   Amendment ........................................................ 15
    7.12   Specific Performance ............................................. 16
    7.13   Jurisdiction; Consent to Service of Process; Waiver .............. 16
    7.14   Waiver of Jury Trial ............................................. 16
    7.15   Further Assurances ............................................... 16
    7.16   Powers of Attorney ............................................... 17
</TABLE>

APPENDIX

Appendix A    Definitions

EXHIBITS:

Exhibit A     Compliance Certificate
Exhibit B     Form of Adoption Agreement
Exhibit C     Form of Adoption Agreement - Wholly Owned Subsidiaries

                                      -ii-

<PAGE>

                             STOCKHOLDERS AGREEMENT

          This STOCKHOLDERS AGREEMENT (this "Agreement"), dated as of ____ __,
2002, is entered into by and among Lyondell Chemical Company, a Delaware
corporation, and the Stockholders.

          The definitions of capitalized terms used in this Agreement are set
forth in Appendix A.

                                    RECITALS

          WHEREAS, Lyondell Chemical Company and Occidental Chemical Holding
Corporation, a California corporation ("OCHC"), entered into a Securities
Purchase Agreement dated as of July 8, 2002 (the "Securities Purchase
Agreement"), governing the sale by the Company to OCHC of Series B Common Stock,
Warrants and contingent consideration;

          WHEREAS, as required by the terms of the Securities Purchase
Agreement, each Stockholder agrees for the benefit of the Company as set forth
in this Agreement;

          NOW, THEREFORE, in consideration of the premises and the
representations, warranties, covenants and agreements contained in this
Agreement, the Parties hereby agree as follows:

                                   SECTION 1

                                      TERM

          1.1 Term. This Agreement is effective as of the date hereof until the
Termination Date. "Termination Date" means, (i) as to Occidental and its Wholly
Owned Affiliates, the date Occidental and its Wholly Owned Affiliates
beneficially own in the aggregate, directly or indirectly, less than [16]
million shares of Common Stock (excluding for purposes of this Section 1.1,
shares to be issued to OCHC or its Subsidiaries upon exercise of a Warrant) and
(ii) as to a transferee that is not a Wholly Owned Affiliate of OCHC, the date
such transferee and its Affiliates beneficially own in the aggregate, directly
or indirectly, less than 5 million shares of Common Stock.

          1.2 Effect of Termination. From and after the Termination Date for a
Stockholder, this Agreement shall become null and void and of no further force
and effect except for the provisions of Sections 1.2, 4.4, 4.5 and 7 (except
Sections 7.15 and 7.16), which shall survive the Termination Date for such
Stockholder. Nothing in this Section 1.2 shall be deemed to release any Party
from any liability for its breach of the terms, conditions and restrictions of
this Agreement before the Termination Date for such Stockholder.

                                       -1-

<PAGE>

                                   SECTION 2

                                   STANDSTILL

          2.1 Standstill. Occidental agrees that neither it nor any of its
Wholly Owned Affiliates, and each Stockholder (other than Occidental and its
Wholly Owned Affiliates) agrees that neither it nor any of its Affiliates,
shall:

          (a) in any manner acquire, agree to acquire or make any proposal to
     acquire, directly or indirectly, any securities of the Company, whether
     such agreement or proposal is made with or to the Company or a third party;

          (b) make any unsolicited inquiry, proposal or offer to enter into,
     directly or indirectly, any sale of all or substantially all assets or
     property of the Company, merger or other similar business combination
     involving the Company;

          (c) make, or in any way participate, directly or indirectly, in any
     "solicitation" of "proxies" (as such terms are used in the proxy rules of
     the SEC) to vote, or seek to advise or influence any Person with respect to
     the voting of, any Voting Securities of the Company;

          (d) except, in the case of Occidental and its Wholly Owned Affiliates,
     for (i) participation by Dr. Ray Irani and/or Stephen I. Chazen on the
     Board of Directors and (ii) subject to Section 3.1, voting in matters
     presented by the Company for a stockholder vote, form, join or in any way
     participate in a "group" (within the meaning of Section 13(d)(3) of the
     Exchange Act) with respect to any Voting Securities of the Company;

          (e) except, in the case of Occidental and its Wholly Owned Affiliates,
     for (i) participation by Dr. Ray Irani and/or Stephen I. Chazen on the
     Board of Directors and (ii) subject to Section 3.1, voting in matters
     presented by the Company for a stockholder vote, otherwise act, alone or in
     concert with others, seek to control or influence the management, Board of
     Directors or policies of the Company;

          (f) except, in the case of Occidental and its Wholly Owned Affiliates,
     for (i) participation by Dr. Ray Irani and/or Stephen I. Chazen on the
     Board of Directors and (ii) subject to Section 3.1, voting in matters
     presented by the Company for a stockholder vote, take any action which
     might reasonably be expected to require the Company to make a public
     announcement regarding the possibility of a merger or other similar
     business combination of the Company;

          (g) except as expressly provided in Section 3.3, seek election to or
     seek to place a representative on the Board of Directors of the Company or
     any of its Affiliates or seek the removal of any member of the Board of
     Directors of the Company or any of its Subsidiaries;

                                       -2-

<PAGE>

          (h) initiate, solicit (or participate in a solicitation) or propose
     the approval of one or more stockholder proposals with respect to the
     Company or any of its Subsidiaries or induce or encourage or attempt to
     induce or encourage any other Person to initiate any such stockholder
     proposal;

          (i) request the Company to, or seek to cause the Company (or its Board
     of Directors) to, call any meeting of the stockholders of the Company or
     any of its Subsidiaries;

          (j) initiate any written consent of the stockholders of the Company or
     sign any written consent of the stockholders of the Company or otherwise
     take any action by any such written consent unless requested to do so by
     the Board of Directors;

          (k) grant or agree to grant any proxy or other voting power to any
     Person other than the Company or other Persons designated by the Company to
     vote at any meeting of the stockholders of the Company, or deposit any
     Voting Securities of the Company in a voting trust or, except as
     specifically contemplated by this Agreement, subject them to a voting
     agreement or other agreement or arrangement with respect to the voting of
     such Voting Securities;

          (l) disclose any intention, plan or arrangement inconsistent with the
     foregoing;

          (m) except, in the case of Occidental and its Wholly Owned Affiliates,
     for (i) participation by Dr. Ray Irani and/or Stephen I. Chazen on the
     Board of Directors and (ii) subject to Section 3.1, voting in matters
     presented by the Company for a stockholder vote, advise, facilitate,
     encourage, provide assistance (including financial assistance) to or hold
     discussions with any other Persons in connection with any of the foregoing;
     or

          (n) request a waiver, modification or amendment by the Board of
     Directors of any of the foregoing restrictions.

          2.2 Exceptions. Notwithstanding Section 2.1:

          (a) Occidental and its Wholly Owned Affiliates may, by notice to the
     Company, suspend the provisions of Section 2.1 at any time within 30
     calendar days after the commencement of a bona fide tender offer or
     exchange offer for outstanding shares of Common Stock of the Company that
     (i) is made by a Person other than the Company or a controlled Affiliate of
     the Company, (ii) is not made pursuant to an agreement between the offeror
     and the Company and (iii) to the extent the consideration offered is cash,
     contains commitments for or evidence of financing sufficient to pay the
     entire cash purchase price; provided, however, that any such suspension
     shall apply only with respect to actions commenced by Occidental and its
     Wholly Owned Affiliates prior to the time the tender or exchange offer of
     such other Person is abandoned or terminated or fails to satisfy clause
     (i), (ii) or (iii) above.

                                       -3-

<PAGE>

          (b) Section 2.1 shall not be applicable to the purchase, directly or
     indirectly, by Occidental and its Wholly Owned Affiliates of up to 320,000
     shares of Original Common Stock in the open market during any Calendar
     Quarter ending after the date hereof so long as after giving effect to such
     purchase, Occidental and its Wholly Owned Affiliates will beneficially own
     in the aggregate, directly or indirectly, a lower ownership percentage in
     the Company than the Occidental Rights Trigger Amount (as defined in the
     Securities Purchase Agreement). Occidental hereby agrees, and shall cause
     its Wholly Owned Affiliates, to promptly notify the Company of the purchase
     of any such shares.

          (c) Section 2.1 shall not be applicable to the exercise of the Warrant
     or the issuance and delivery by the Company to a Stockholder of (i) PIK
     Shares, (ii) Conversion Shares, (iii) Contingent Shares, (iv) Warrant
     Shares, (v) Net Payment Shares or (vi) the Initial Shares.

                                   SECTION 3

            VOTING PROVISIONS; BOARD APPOINTMENTS; GOVERNANCE MATTERS

          3.1 Voting Agreement. Occidental agrees, and shall cause its Wholly
Owned Affiliates to agree, and each Stockholder (other than Occidental and its
Wholly Owned Affiliates) agrees, and shall cause its Affiliates to agree, that
until the Termination Date for such Stockholder, each share of each class of
Voting Securities of the Company beneficially owned, directly or indirectly, by
such Stockholder and its Affiliates shall be "present" for the taking of any
Stockholder action and voted "for" the nominees to the Board of Directors
proposed by the Continuing Directors. The provisions of this Section 3.1 shall
apply to both the casting of votes at a general or special meeting of
stockholders of the Company and any execution of stockholder action by written
consent. Each Stockholder agrees and shall, and shall cause its Affiliates to
(i) execute and deliver to the Secretary of the Company not later than 20
calendar days prior to the date of any general meeting of stockholders of the
Company a proxy (in such form as provided by and on behalf of the Board of
Directors) representing all Voting Securities of the Company beneficially owned,
directly or indirectly, by such Stockholder and its Affiliates voted in
accordance with the provisions of this Section 3.1 and (ii) take similar or
analogous action with respect to a request for written consents from
Stockholders of the Company.

          3.2 Proxies and Voting Agreements. Each Stockholder hereby revokes any
and all previous proxies granted with respect to matters set forth in Section
3.1. Except as contemplated hereby, no Stockholder shall, directly or
indirectly, grant any proxies or powers of attorney, deposit, or enter into a
voting agreement with respect to, any Voting Securities of the Company with
respect to matters set forth in Section 3.1.

          3.3 Board Appointments.

          (a) The Company shall exercise all authority under applicable law to
     cause Dr. Ray Irani and Stephen I. Chazen to be appointed as directors of
     the Company effective as of the date hereof. The Parties agree that if
     either such individual is at any time unable, unwilling or not qualified to
     serve as a director of the Company, neither

                                       -4-

<PAGE>

     Occidental, its Subsidiaries nor any other Person shall have the right to
     name a substitute or to require that a different individual be appointed to
     the Board of Directors.

          (b) The Company shall exercise all authority under applicable law to
     cause any slate of directors presented to the stockholders of the Company
     for election to the Board of Directors to include both Dr. Ray Irani and
     Stephen I. Chazen, so long as they are qualified to serve, until Occidental
     and its Subsidiaries beneficially own in the aggregate, directly or
     indirectly, less than [32] million shares of Common Stock (excluding for
     purposes of this Section 3.3(b), shares to be issued to OCHC or its Wholly
     Owned Affiliates upon exercise of a Warrant), from which time until the
     Termination Date for Occidental and its Wholly Owned Affiliates only one of
     such individuals (to be determined in the sole discretion of the Company)
     shall be entitled to a seat on the Board of Directors.

          3.4 Conversion of Shares of Series B Common Stock into Shares of
Original Common Stock.

          (a) Occidental agrees, and shall cause its Wholly Owned Affiliates to
     agree, and each Stockholder (other than Occidental and its Wholly Owned
     Affiliates) agrees, and shall cause its Affiliates to agree, that,
     notwithstanding the terms of conversion set forth in Article IV, Section
     II(6)(a) of the Amended and Restated Certificate, any shares of Series B
     Common Stock beneficially owned by a Stockholder that are Initial Shares,
     Net Payment Shares, Contingent Shares or PIK Shares may be converted into
     shares of Original Common Stock at the option of a Stockholder only at any
     time:

              (i)   after ___________, 2005/1/;

              (ii)  after ____________, 2004/2/, but only if the Company would
                    be entitled, without breach or violation of any of the
                    covenants in the indentures and other agreements governing
                    its indebtedness outstanding at such time (and without
                    reliance on Section 4.07(b)(xv) of the Indenture dated as of
                    May 17, 1999 between the Company and The Bank of New York,
                    as Trustee, relating to the Company's Senior Secured Notes
                    2007 or any like provision of any other indenture to which
                    the Company is a party), to pay, immediately after
                    conversion of the outstanding shares of Series B Common
                    Stock proposed to be converted, cash dividends on the shares
                    of Series B Common Stock to be converted at the same rate
                    per share as the Company paid on its outstanding shares of
                    Original Common Stock on the last dividend payment date
                    immediately preceding such time, all as reasonably
                    determined in good faith by the Company;

              (iii) with the prior written consent of the Company, pursuant to
                    action by the Board of Directors; or

--------------------
1 The date that is the third anniversary of the first issuance of Series B
Common Stock will be inserted.
2 The date that is the second anniversary of the first issuance of Series B
Common Stock will be inserted.

                                       -5-

<PAGE>

              (iv)   following an acquisition by any person of a majority of the
                     outstanding Voting Securities of the Company in a
                     transaction not approved by the Board of Directors.

          (b) If the timing of the conversion so requires, then, in addition to
     the items set forth in Article IV, Section 6(c)(i) of the Amended and
     Restated Certificate, each share of Series B Common Stock submitted to the
     Company for conversion shall also be accompanied by a certified copy of the
     resolutions of the Board of Directors consenting to the conversion or
     stating that the conditions for conversion set forth in this Section 3.4
     have been satisfied. If OCHC or its Wholly Owned Affiliate request
     conversion of one or more shares of Series B Common Stock and the timing of
     such conversion requires a certified copy of resolutions of the Board of
     Directors consenting to such conversion or stating that the conditions for
     conversion set forth in this Section 3.4 have been satisfied, the Board of
     Directors shall promptly consider such conversion and provide OCHC or its
     Wholly Owned Affiliate, as applicable, with certified resolutions
     reflecting the results of such consideration.

          (c) From the date hereof until the date OCHC and its Wholly Owned
     Affiliates cease to beneficially own in the aggregate, directly or
     indirectly, shares of Series B Common Stock eligible for conversion
     pursuant to this Section 3.4 and Article IV, Section 6 of the Amended and
     Restated Certificate, the Company shall cause the time period commencing
     with the date a dividend is declared on shares of the Series B Common Stock
     and the related record date to not exceed sixty calendar days unless
     otherwise required by applicable law.

          3.5 Number of Authorized Shares of Series B Common Stock. (a) From the
date hereof until the Termination Date for OCHC and its Wholly Owned Affiliates,
the Company shall not effect an amendment to the Amended and Restated
Certificate (whether by merger, consolidation or otherwise) that increases the
number of authorized shares of Series B Common Stock without the prior written
consent of OCHC.

                                    SECTION 4

                                    TRANSFERS

          4.1 Transfers.

          (a) No Stockholder may Transfer a Subject Security except as permitted
     by and in accordance with Sections 4.1(b) or 4.1(c).

          (b) A Stockholder may Transfer, subject to applicable laws, Warrant
     Shares, Conversion Shares, Net Payment Shares (Original) and Contingent
     Shares (Original) as follows:

              (i)   pursuant to a registered public offering in accordance with
                    the terms and conditions of the Registration Rights
                    Agreement (a "Registered Public Offering");

                                       -6-

<PAGE>

                    (ii)  pursuant to Rule 144 of the Securities Act in an
                          unsolicited "broker's transaction" (as defined in Rule
                          144 of the Securities Act) on a securities exchange in
                          compliance with the volume limitations set forth in
                          Rule 144(e) of the Securities Act (regardless of
                          whether such volume limitations are applicable by law
                          to the transferor Stockholder); or

                    (iii) in connection with a sale of not more than 15 million
                          shares in a single transaction or series of related
                          transactions.

               (c)  OCHC may Transfer any Subject Security to any Wholly Owned
          Affiliate.

               (d)  Notwithstanding the restrictions on Transfer set forth in
          this Section 4.1, a Stockholder may mortgage, pledge, encumber or
          create or suffer to exist any pledge, lien or encumbrance upon or
          security interest in ("Pledge") all or part of its Subject Securities
          to any one or more Approved Lenders; provided that the Pledge shall be
          evidenced by an instrument, the form of which shall be reasonably
          satisfactory to the Company, wherein the Approved Lender receiving
          such Pledge shall agree that in the event it obtains a right of
          foreclosure on a Stockholder's Subject Securities, such Approved
          Lender shall (i) assume all of the obligations of such Stockholder
          hereunder and (ii) be bound by the terms, conditions and restrictions
          set forth in this Agreement. The term "Pledge" is used herein both as
          a noun and as a verb. The term "Approved Lender" is used herein to
          mean any bank, insurance company, investment bank or other financial
          institution that is regularly engaged in the business of making loans.

               4.2  Compliance Certificate; Adoption Agreement.

               (a)  As a condition to the Company's obligation to effect a
          Transfer permitted under Section 4.1(b), the transferor Stockholder
          shall execute and deliver a certificate of compliance with Section
          4.1(b) in the form of Exhibit A attached hereto or in such other form
          that is reasonably satisfactory to the Company. In addition, any
          transferee (other than a QIB) who acquires five million or more
          Subject Shares pursuant to a Transfer in accordance with Section
          4.1(b) and such transferee's ultimate parent entity shall execute an
          Adoption Agreement in the form of Exhibit B attached hereto or in such
          other form that is reasonably satisfactory to the Company.

               (b)  As a condition to the Company's obligation to effect a
          Transfer permitted under Section 4.1(c), any transferee of Subject
          Securities shall execute an Adoption Agreement in the form of Exhibit
          C attached hereto or in such other form that is reasonably
          satisfactory to the Company.

               4.3  Invalid Transfers. Any Transfer of Subject Securities
contrary to the provisions of this Section 4 shall be null and void, and the
transferee shall not be recognized by the Company as the holder or owner of such
Subject Security Transferred for any purpose (including voting or dividend
rights), unless and until the requirements of Sections 4.1, 4.2, 4.4 and 4.5
have been satisfied. No Subject Security shall be transferred on the books of
the Company until each of such provisions have been satisfied.

                                  -7-

<PAGE>

               4.4  Compliance with Securities Laws. No Stockholder shall
Transfer its interest in a Subject Security at any time if such action would
constitute a violation of any federal or state securities or blue sky laws or a
breach of the conditions to any exemption from registration of such Subject
Security under any such laws or a breach of any undertaking or agreement of a
Stockholder entered into pursuant to such laws or in connection with obtaining
an exemption thereunder, and, except in the case of a Registered Public
Offering, the Company shall not be required to transfer upon its books such
Subject Security unless prior thereto the Company shall have received an opinion
of counsel in form and substance reasonably satisfactory to the Company that
such transaction is in compliance with this Section 4.4. This Section 4.4 shall
survive termination of this Agreement for the maximum period permitted by
applicable law.

               4.5  Restrictive Legends.

               (a)  A copy of this Agreement will be filed with the Secretary of
          the Company and kept with the records of the Company.

               (b)  All certificates representing shares of Subject Shares shall
          bear the following legend noted conspicuously on such certificates:

                    THE SHARES REPRESENTED BY THIS CERTIFICATE HAVE
                    BEEN ACQUIRED FOR INVESTMENT AND HAVE NOT BEEN
                    REGISTERED UNDER THE SECURITIES ACT OF 1933, AS
                    AMENDED, OR ANY STATE SECURITIES LAWS. SUCH SHARES
                    MAY NOT BE SOLD OR TRANSFERRED IN THE ABSENCE OF
                    SUCH REGISTRATION OR AN OPINION OF COUNSEL
                    SATISFACTORY TO THE COMPANY AS TO THE AVAILABILITY
                    OF AN EXEMPTION FROM REGISTRATION AND THAT SUCH
                    REGISTRATION IS NOT REQUIRED.

                    THE SHARES EVIDENCED BY THIS CERTIFICATE ARE
                    SUBJECT TO RESTRICTIONS ON TRANSFER AS SET FORTH
                    IN A STOCKHOLDERS AGREEMENT. NO TRANSFER OF THESE
                    SHARES WILL BE EFFECTIVE UNLESS AND UNTIL THE
                    TERMS AND CONDITIONS OF SUCH STOCKHOLDERS
                    AGREEMENT HAVE BEEN COMPLIED WITH IN FULL AND NO
                    PERSON MAY REQUEST THE COMPANY TO RECORD THE
                    TRANSFER OF ANY SHARES IF SUCH TRANSFER IS IN
                    VIOLATION OF SUCH STOCKHOLDERS AGREEMENT. A COPY
                    OF SUCH STOCKHOLDERS AGREEMENT MAY BE OBTAINED AT
                    NO COST BY WRITTEN REQUEST MADE BY THE HOLDER OF
                    RECORD OF THIS CERTIFICATE TO THE SECRETARY OF THE
                    COMPANY AT THE PRINCIPAL EXECUTIVE OFFICES OF THE
                    COMPANY. THE SHARES EVIDENCED BY THIS CERTIFICATE
                    ARE SUBJECT TO RESTRICTIONS

                                  -8-

<PAGE>

                    ON VOTING PROVIDED FOR IN SUCH STOCKHOLDERS
                    AGREEMENT AND NO VOTE OF SUCH SHARES THAT
                    CONTRAVENES SUCH STOCKHOLDERS AGREEMENT SHALL BE
                    EFFECTIVE.

               (c)  All certificates representing Warrants will bear the
          following legend noted conspicuously on such certificates:

                    THE SECURITIES REPRESENTED BY THIS CERTIFICATE
                    HAVE BEEN ACQUIRED SOLELY FOR INVESTMENT AND HAVE
                    NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF
                    1933, AS AMENDED, OR ANY STATE SECURITIES LAWS.
                    SUCH SECURITIES MAY NOT BE SOLD OR TRANSFERRED IN
                    THE ABSENCE OF SUCH REGISTRATION OR AN OPINION OF
                    COUNSEL FOR THE HOLDER REASONABLY SATISFACTORY TO
                    THE COMPANY AS TO THE AVAILABILITY OF AN EXEMPTION
                    FROM REGISTRATION AND THAT SUCH REGISTRATION IS
                    NOT REQUIRED.

                    THE SECURITIES REPRESENTED BY THIS CERTIFICATE ARE
                    SUBJECT TO RESTRICTIONS ON TRANSFER AS SET FORTH
                    IN A STOCKHOLDERS AGREEMENT. NO TRANSFER OF THE
                    SECURITIES REPRESENTED BY THIS CERTIFICATE SHALL
                    BE EFFECTIVE UNLESS AND UNTIL THE TERMS AND
                    CONDITIONS OF SUCH STOCKHOLDERS AGREEMENT HAVE
                    BEEN COMPLIED WITH IN FULL AND NO PERSON MAY
                    REQUEST THE COMPANY TO RECORD THE TRANSFER OF ANY
                    SUCH SECURITIES IF SUCH TRANSFER IS IN VIOLATION
                    OF SUCH STOCKHOLDERS AGREEMENT. THE SHARES TO BE
                    ISSUED UPON EXERCISE OF THIS WARRANT ARE SUBJECT
                    TO RESTRICTIONS ON VOTING PROVIDED FOR IN SUCH
                    STOCKHOLDERS AGREEMENT AND NO VOTE OF SUCH SHARES
                    THAT CONTRAVENES SUCH STOCKHOLDERS AGREEMENT SHALL
                    BE EFFECTIVE. A COPY OF SUCH STOCKHOLDERS
                    AGREEMENT MAY BE OBTAINED AT NO COST BY WRITTEN
                    REQUEST MADE BY THE HOLDER OF RECORD OF THIS
                    CERTIFICATE TO THE SECRETARY OF THE COMPANY AT THE
                    PRINCIPAL EXECUTIVE OFFICES OF THE COMPANY.

                                  -9-

<PAGE>

               (d)  All certificates representing shares of Original Common
               Stock acquired by a Stockholder in the open market will bear the
               following legend noted conspicuously on such certificates:

                    THE SHARES REPRESENTED BY THIS CERTIFICATE ARE
                    SUBJECT TO RESTRICTIONS ON VOTING PROVIDED FOR IN
                    A STOCKHOLDERS AGREEMENT AND NO VOTE OF SUCH
                    SHARES THAT CONTRAVENES SUCH STOCKHOLDERS
                    AGREEMENT SHALL BE EFFECTIVE. A COPY OF SUCH
                    STOCKHOLDERS AGREEMENT MAY BE OBTAINED AT NO COST
                    BY WRITTEN REQUEST OF THE RECORD HOLDER OF THIS
                    CERTIFICATE TO THE SECRETARY OF THE COMPANY AT THE
                    PRINCIPAL EXECUTIVE OFFICES OF THE COMPANY.

               (e)  Until such time as a Subject Security held by a Stockholder
          has been registered pursuant to a registration statement under the
          Securities Act in accordance with the terms and provisions of the
          Registration Rights Agreement, the certificates representing such
          Subject Security (including all certificates issued upon Transfer or
          in exchange thereof or substitution therefor) will also bear any
          legend required under any other applicable laws, including state
          securities or blue sky laws.

               (f)  In the event a Stockholder and/or its Affiliates acquire
          beneficial ownership, directly or indirectly, of any other or
          additional securities of the Company, such Stockholder shall, and
          shall cause its Affiliate, if applicable, to, submit all certificates
          representing such securities to the Company so that the legend or
          legends required by this Section 4.5 may be placed thereon.

               (g)  The Company may make a notation on its records or give
          stop-transfer instructions to any transfer agents or registrars for
          the Subject Securities in order to implement the restrictions set
          forth in this Section 4.

                                    SECTION 5

                        REGISTRATION RIGHTS; ADJUSTMENTS

               5.1  Registration Rights. The Stockholders shall have such
registration rights as are set forth in the Registration Rights Agreement.

               5.2  Adjustments. If the Company at any time during the term of
this Agreement subdivides its outstanding Original Common Stock or issues a
stock dividend in Original Common Stock, the share amounts referred to in this
Agreement shall be proportionately increased. If the Company at any time during
the term of this Agreement combines its outstanding Original Common Stock, the
share numbers referred to in this Agreement shall be proportionately decreased.
Any adjustment made pursuant to this Section 5.2 shall become effective
immediately after the effective date of such event retroactive to the record
date, if any, for such event.

                                 -10-

<PAGE>

                                    SECTION 6

               REPRESENTATIONS AND WARRANTIES OF THE STOCKHOLDERS

               Each Stockholder represents and warrants to the Company
that as of the date hereof:

               6.1  Organization. Such Stockholder is duly organized, validly
existing and in good standing under the laws of the jurisdiction in which such
Stockholder was incorporated or formed.

               6.2  Corporate Power and Authority. Such Stockholder has all
requisite corporate power and authority, or power under its constituent
documents, to enter into this Agreement and to perform its obligations
hereunder. The execution, delivery and performance by such Stockholder of this
Agreement have been duly authorized by all necessary corporate or similar action
on the part of such Stockholder.

               6.3  Binding Effect. This Agreement has been duly executed and
delivered by such Stockholder and is a valid and binding agreement of such
Stockholder, enforceable against such Stockholder in accordance with its terms,
except as enforcement may be limited by bankruptcy, insolvency, reorganization,
moratorium or other similar laws relating to creditors' rights generally and by
equitable principles to which the remedies of specific performance and
injunctive and similar forms of relief are subject.

               6.4  Ownership. Such Stockholder beneficially owns in the
aggregate, directly or indirectly, the amount of securities of the Company set
forth next to its name on the signature page hereto, the Stockholder has the
sole right to vote such securities, as applicable, and, other than this
Agreement, there are no restrictions on rights of disposition or Pledge, charge
or other encumbrance or restriction pertaining to such securities. Except as
provided herein, none of such securities is subject to any voting trust or other
agreement, arrangement or restriction with respect to the voting of such
securities, and no proxy, power of attorney or other authorization has been
granted with respect to any of such securities. Such Stockholder is not a party
to any option, warrant, purchase right, or other contract or commitment that
could require such Stockholder to Transfer or otherwise dispose of any capital
stock of the Company (other than this Agreement). Such Stockholder is not a
party to any voting trust, proxy or other agreement or understanding with
respect to Voting Securities of the Company (other than this Agreement).

               6.5  Total Shares. The securities of the Company listed next to
such Stockholder's name on the signature page hereto are the only securities of
the Company beneficially owned in the aggregate, directly or indirectly, by such
Stockholder, and, other than the Warrant, such Stockholder does not have any
option to purchase or right to subscribe for or otherwise acquire any additional
securities of the Company and has no other interest in or voting rights with
respect to any other securities of the Company. No Wholly Owned Affiliate of
such Stockholder beneficially owns any securities of the Company (other than a
Wholly Owned Affiliate who is also a Party).

                                      -11-

<PAGE>

          6.6 Finder's Fees. No investment banker, broker or finder is entitled
to a commission or fee from such Stockholder in respect of this Agreement based
upon any arrangement or agreement made by or on behalf of the Stockholder,
except as otherwise provided in the Securities Purchase Agreement, if a party
thereto.

          6.7 Investment. Such Stockholder is acquiring the Subject Securities
for investment for its own account, not as a nominee or agent, and not with a
view to, or for resale in connection with, any distribution thereof in violation
of applicable law, and has not offered or sold any portion of the Subject
Securities to be acquired by it. Such Stockholder acknowledges and understands
that investment in the Subject Securities is subject to a high degree of risk
and that it must bear the economic risk of its investment for an indefinite
period of time because the Subject Securities must be held indefinitely (i)
until subsequently registered under the Securities Act and applicable state and
other securities laws or (ii) unless an exemption from registration is available
which depends upon, among other things, the bona fide nature of such
Stockholder's investment intent and the accuracy of such Stockholder's
representations as expressed herein. Such Stockholder understands that any
transfer agent of the Company will issue stop transfer instructions with respect
to the Subject Securities unless such Transfer is subsequently registered under
the Securities Act and applicable state and other securities laws or unless an
exemption from such registration is available. Such Stockholder was not
organized for the purpose of acquiring the Subject Securities.

          6.8 Investigation; No General Solicitation. Such Stockholder has
received a copy of the Company SEC Reports. Such Stockholder has had a
reasonable opportunity to ask questions relating to and otherwise discuss with
the Company's management and other parties (i) the terms and conditions of the
offering, (ii) the other information set forth in the Company SEC Reports and
the Securities Purchase Agreement, if a party thereto, and (iii) this Agreement
and the Company's business, management and financial affairs, and such
Stockholder has received satisfactory responses to such Stockholder's inquiries.
To the extent necessary, such Stockholder has retained, at the expense of such
Stockholder, and relied upon appropriate professional advice regarding the
investment, tax and legal merits and consequences of this Agreement, the
Securities Purchase Agreement, if a party thereto, and its acquisition of
Subject Securities. Such Stockholder has relied only on its own independent
investigation and on the representations and warranties of the Company contained
herein and in the Securities Purchase Agreement, if a party thereto, before
deciding to acquire such Subject Securities.

          6.9 Sophistication and Financial Condition of Stockholder. Such
Stockholder is an experienced and sophisticated investor and has such knowledge
and experience in financial and business matters or its professional advisors
have such knowledge and experience in financial and business matters as are
necessary to evaluate the merits and risks of an investment in the Subject
Securities and to evaluate the merits and risks of its investment and protect
its own interest in connection with the acquisition of a Subject Security. Such
Stockholder is able to bear the economic risk of this investment regarding the
Company, is able to hold the Subject Securities indefinitely and has a
sufficient net worth to sustain a loss of its entire investment in the Company
in the event such loss should occur.

                                       -12-

<PAGE>

          6.10 Status of Subject Securities. Such Stockholder has been informed
by the Company that the Subject Securities have not been and will not be
registered under the Securities Act or under any state securities laws,
including Section 25102(f) of the California Corporations Code, except as
specifically provided in the Registration Rights Agreement, and are being
offered and sold in reliance upon federal and state exemptions for transactions
not involving any public offering. Such Stockholder acknowledges that any
certificate representing Subject Securities will bear the legend or legends
specified in Section 4.5.

          6.11 Government Consent. Except as may be required under the HSR Act
and such filings as may be required to be made with the SEC, or under state
securities or blue sky laws, no consent, approval or authorization of or
designation, declaration or filing with any governmental authority on the part
of the Purchaser is required in connection with the valid execution and delivery
of this Agreement or the acquisition of the Subject Securities.

                                    SECTION 7

                                  MISCELLANEOUS

          7.1 Successors and Assigns. Except as may be expressly provided
herein, this Agreement shall be binding upon and inure to the benefit of the
successors of each of the Parties hereto. No Party may otherwise assign or
delegate any of its rights or obligations under this Agreement by operation of
law or otherwise (other than as a result of any merger or consolidation) without
the prior written consent of the other Parties, which consent shall be in the
sole and absolute discretion of such other Parties. Any purported assignment or
delegation without such consent shall be void and ineffective.

          7.2 Certain Events. Such Stockholder agrees that this Agreement and
the obligations hereunder shall attach to the Subject Securities and shall be
binding upon any person to which beneficial ownership, directly or indirectly,
of such Subject Securities shall pass, whether by operation of law or otherwise.

          7.3 Benefits of Agreement Restricted to Parties. This Agreement is
made solely for the benefit of the Parties, and no other Person (including each
Party's employees or stockholders) shall have any right, claim or cause of
action under or by virtue of this Agreement.

          7.4 Notices. All notices, requests and other communications
(collectively, the "Notices") made pursuant to this Agreement shall be in
writing and signed and correctly dated by the Party sending such Notice. All
Notices shall be delivered personally (by courier or otherwise) or by facsimile
to the receiving Party at the applicable address or facsimile number set forth
below:

          If to the Company:

                   Lyondell Chemical Company
                   1221 McKinney Street, Suite 700
                   Houston, Texas 77010
                   Attention: Gerald A. O'Brien
                   Telecopy Number:  713-652-4538

                                      -13-

<PAGE>

                   with a copy to:

                   Baker Botts L.L.P.
                   910 Louisiana Street
                   Houston, Texas  77002
                   Attention:  Stephen A. Massad
                   Telecopy Number:  713-229-1522

                   and

                   Lyondell Chemical Company
                   1221 McKinney Street, Suite 700
                   Houston, Texas 77010
                   Attention: General Counsel
                   Telecopy Number:  713-309-7312

          If to a Person who is a Stockholder on the date hereof:

                   Occidental Petroleum Corporation
                   10889 Wilshire Boulevard
                   Los Angeles, California 90024
                   Attention: General Counsel
                   Telecopy Number: 310-443-6195

                   Occidental Chemical Holding Corporation
                   505 LBJ Freeway
                   Dallas, Texas  75244
                   Attention: General Counsel
                   Telecopy Number: 972-404-4155

Any Notice delivered personally shall be deemed to have been given on the date
it is so delivered, or upon attempted delivery if acceptance of delivery is
refused, and any Notice delivered by facsimile shall be deemed to have been
given on the first Business Day it is received by the addressee (or, if such
Notice is not received during regular business hours of a Business Day, at the
beginning of the next such Business Day). The address and facsimile numbers set
forth above may be changed by a Party by giving Notice of such change of address
or facsimile number in the manner set forth in this Section 7.4.

          7.5 Severability. In the event that any provision of this Agreement
shall finally be determined to be unlawful, such provision shall be deemed
severed from this Agreement and every other provision of this Agreement shall
remain in full force and effect. If the economic and legal substance of the
rights and obligations of the Parties are affected in any materially adverse
manner as to any of the Parties and the Parties cannot agree on a lawful
substitute provision, the adversely affected Party shall have the right to
terminate this Agreement immediately upon notice to the other Parties.

                                      -14-

<PAGE>

          7.6  Construction. In construing this Agreement, the following
principles shall be followed: (i) no consideration shall be given to the
captions of the articles, sections, subsections or clauses, which are inserted
for convenience in locating the provisions of this Agreement and not as an aid
in construction; (ii) no consideration shall be given to the fact or presumption
that any of the Parties had a greater or lesser hand in drafting this Agreement;
(iii) the word "includes" and its syntactic variants mean "includes, but is not
limited to" and corresponding syntactic variant expressions; (iv) the plural
shall be deemed to include the singular, and vice versa; (v) references in this
Agreement to Articles, Sections, Appendices and Exhibits shall be deemed to be
references to Articles and Sections of, and Appendices and Exhibits to, this
Agreement unless the context shall otherwise require; (vi) all Exhibits and
Appendices attached to this Agreement shall be deemed incorporated herein as if
set forth in full herein; (vii) the words "hereof", "herein" and "hereunder" and
words of similar import shall refer to this Agreement as a whole and not to any
particular provision of this Agreement; (viii) references to a Person are also
to its permitted successors and permitted assigns; and (ix) unless otherwise
expressly provided, any agreement, instrument or statute defined or referred to
herein means such agreement, instrument or statute as from time to time amended,
modified or supplemented, including (in the case of agreements or instruments)
by waiver or consent and (in the case of statutes) by succession of comparable
successor statutes and references to all attachments thereto and instruments
incorporated therein.

          7.7  Entire Agreement. This Agreement together with the Related
Securities Agreements sets forth the entire agreement and understanding among
the Parties as to the subject matter hereof and merges with and supercedes all
prior discussions, agreements and understandings of every kind and nature among
them.

          7.8  Counterparts. This Agreement may be executed in one or more
counterparts, each of which shall constitute an original, and all of which when
taken together shall constitute one and the same original document.

          7.9  Governing Law. The laws of the State of Delaware shall govern the
construction, interpretation and effect of this Agreement without giving effect
to any conflicts of law principles.

          7.10 Transaction Costs. Each Party shall be solely responsible for and
bear all of its own respective costs, fees and expenses.

          7.11 Amendment. All waivers, modifications, amendments or alterations
of this Agreement shall require the written approval of each of the Parties.
Except as provided in the preceding sentence, no action taken pursuant to this
Agreement, including any investigation by or on behalf of any Party, shall be
deemed to constitute a waiver by the Party taking such action of compliance with
any representations, warranties, covenants or agreements contained herein. The
waiver by any Party of a breach of any provision of this Agreement shall not
operate or be construed as a waiver of any subsequent breach.

                                      -15-

<PAGE>

          7.12 Specific Performance. Each Party agrees that the other Parties
would be irreparably damaged if for any reason such Party fails to perform any
of such Party's obligations under this Agreement, and that the other Parties
would not have an adequate remedy at law for money damages in such event.
Accordingly, the other Parties shall be entitled to seek specific performance
and injunctive and other equitable relief to enforce the performance of this
Agreement by such Party. This provision is without prejudice to any other rights
that the Parties may have against any other Party for any failure to perform its
obligations under this Agreement.

          7.13 Jurisdiction; Consent to Service of Process; Waiver. ANY JUDICIAL
PROCEEDING BROUGHT AGAINST ANY PARTY OR ANY DISPUTE UNDER, ARISING OUT OF OR IN
CONNECTION WITH THIS AGREEMENT SHALL BE BROUGHT IN THE FEDERAL OR STATE COURTS
OF THE STATE OF DELAWARE, AND, BY EXECUTION AND DELIVERY OF THIS AGREEMENT, EACH
OF THE PARTIES ACCEPTS THE EXCLUSIVE JURISDICTION OF SUCH COURTS AND IRREVOCABLY
AGREES TO BE BOUND BY ANY JUDGMENT (AS FINALLY ADJUDICATED) RENDERED THEREBY IN
CONNECTION WITH THIS AGREEMENT. EACH OF THE PARTIES SHALL APPOINT THE
CORPORATION TRUST COMPANY, THE PRENTICE-HALL CORPORATION SYSTEM, INC. OR A
SIMILAR ENTITY (THE "AGENT") AS AGENT TO RECEIVE ON ITS BEHALF SERVICE OF
PROCESS IN ANY PROCEEDING IN ANY SUCH COURT IN THE STATE OF DELAWARE, AND EACH
OF THE PARTIES SHALL MAINTAIN THE APPOINTMENT OF SUCH AGENT (OR A SUBSTITUTE
AGENT) FROM THE DATE HEREOF UNTIL THE TERMINATION OF THIS AGREEMENT AND
SATISFACTION OF ALL OBLIGATIONS HEREUNDER. THE FOREGOING CONSENTS TO
JURISDICTION AND APPOINTMENTS OF AGENT TO RECEIVE SERVICE OF PROCESS SHALL NOT
CONSTITUTE GENERAL CONSENTS TO SERVICE OF PROCESS IN THE STATE OF DELAWARE FOR
ANY PURPOSE EXCEPT AS PROVIDED ABOVE AND SHALL NOT BE DEEMED TO CONFER RIGHTS ON
ANY PERSON OTHER THAN THE PARTIES. EACH PARTY HEREBY WAIVES ANY OBJECTION IT MAY
HAVE BASED ON LACK OF PERSONAL JURISDICTION, IMPROPER VENUE OR FORUM
NON-CONVENIENS.

          7.14 Waiver of Jury Trial. EACH PARTY HEREBY KNOWINGLY AND
INTENTIONALLY, IRREVOCABLY AND UNCONDITIONALLY WAIVES TRIAL BY JURY IN ANY LEGAL
ACTION OR PROCEEDING UNDER, ARISING OUT OF OR IN CONNECTION WITH THIS AGREEMENT
AND FOR ANY COUNTERCLAIM THEREIN.

          7.15 Further Assurances. From time to time, at the request of any
other Party, each Party shall execute and deliver or cause to be executed and
delivered such additional documents and instruments and take all such further
action as may be necessary or desirable to consummate the transactions
contemplated by this Agreement. When and if applicable, each Stockholder shall
cooperate with the Company and timely comply with requests for information by
the Company which the Company may be required to seek pursuant to Temporary
Treasury Regulation Section 1.382-2T(k)(3).

                                       -16-

<PAGE>

          7.16 Powers of Attorney. For the purpose of executing an Adoption
Agreement, each Stockholder hereby appoints the Company as agent and attorney of
such Stockholder to execute such Adoption Agreement on their behalf and
expressly bind themselves to the Adoption Agreement by the Company's execution
of that Adoption Agreement without further action on their part. On the
execution of an Adoption Agreement by the Company and any Person, such Person
shall be bound by, and shall have the benefit of, all the terms and conditions
set out in this Agreement to the same extent as if such Person were a
"Stockholder" as defined in this Agreement.

                                      -17-

<PAGE>

          IN WITNESS WHEREOF, this Stockholders Agreement has been executed on
behalf of each of the Parties by their respective officers thereunto duly
authorized, effective as of the date first written above.

                                                    LYONDELL CHEMICAL COMPANY

                                                    By:_________________________
                                                       Name:
                                                       Title:

<PAGE>

                                  STOCKHOLDERS

<TABLE>
<CAPTION>
                                                      Shares and Warrants Beneficially Owned
                                                                at Time of Execution
                                     ------------------------------------------------------------------------
                                            Original               Series B Common
Stockholder                               Common Stock                  Stock                  Warrants
-----------                          -----------------------     --------------------    ---------------------
                                       (Includes Subject
                                       Shares and shares
                                     acquired in the open
                                             market)
<S>                                  <C>                           <C>                         <C>
Occidental Chemical Holding
Corporation

By:________________________________  _______________________     ____________________    _____________________
Name:
Title:

Occidental Petroleum Corporation*

By:________________________________  _______________________     ____________________    _____________________
Name:
Title:
</TABLE>

*Note: Amounts listed do not include those shares and warrants beneficially
owned by OCHC.

<PAGE>

                                   APPENDIX A
                                       TO
                             STOCKHOLDERS AGREEMENT

                                   DEFINITIONS

          "Affiliate" shall mean any Person that directly or indirectly through
one or more intermediaries, controls, or is controlled by, or is under common
control with, the Person specified; provided, however, that for purposes of this
Agreement neither the Partnership nor any entity controlled by it shall be
considered an Affiliate of the Company or of the Purchaser. For purposes of this
definition, the term "control" shall have the meaning set forth in 17 CFR
230.405 as in effect on the date hereof.

          "Agreement" shall mean this Stockholders Agreement entered into among
the Parties as of the date hereof.

          "Amended and Restated Certificate" shall mean the Amended and Restated
Certificate of Incorporation of Lyondell Chemical Company that was filed with
the Secretary of State of the State of Delaware on [______], 2002.

          "Approved Lender" shall have the meaning set forth in Section 4.1(d).

          A Person shall be deemed to "beneficially own," or to have "beneficial
ownership" of, any securities of the Company (which securities shall also be
deemed "beneficially owned" by such Person) that such Person is deemed to
"beneficially own" within the meaning of Rule l3d-3 under the Exchange Act.

          "Board of Directors" shall mean the Board of Directors of the Company
and any duly authorized committee thereof.

          "Business Day" shall mean any day on which the New York Stock
Exchange, Inc. is open for trading.

          "Calendar Quarter" shall mean any of the following periods or any
portion thereof: (i) January 1 through March 31; (ii) April 1 through June 31;
(iii) July 1 through September 30; or (iv) October 1 through December 31.

          "Change of Control" shall mean, as to any Party, the occurrence of any
of the following events: (a) there shall be consummated any consolidation,
merger or share exchange of such Party; (b) substantially all of such Party's
properties or assets are sold or otherwise disposed of to any Person or group of
Persons in any one transaction or a series of related transactions; or (c) any
Transfer of the Voting Securities of such Party.

          "Common Stock" shall mean the Original Common Stock and the Series B
Common Stock.

                              Appendix A - Page 1

<PAGE>

          "Combined Voting Power" shall mean the aggregate votes entitled to be
cast generally in the election of the board of directors, or similar managing
group, of a corporation or other entity by holders of then outstanding Voting
Securities of such corporation or other entity.

          "Company" shall mean Lyondell Chemical Company, a Delaware
corporation, or any Surviving Entity.

          "Company SEC Reports" shall mean the forms, reports and documents
required to be filed by the Company with the SEC since December 31, 2001.

          "Contingent Shares" shall mean the shares of Original Common Stock or
Series B Common Stock that are issued to satisfy the Company's obligation to pay
a Contingent Payment Amount (as defined in the Securities Purchase Agreement).

          "Contingent Shares (Original)" shall mean the Contingent Shares that
are shares of Original Common Stock.

          "Continuing Directors" shall mean, as of any date of determination,
any member of the Board of Directors who (i) was a member of the Board of
Directors on the date of this Agreement or (ii) was nominated for election to
the Board of Directors with the affirmative vote of a majority of the Continuing
Directors who were members of such Board of Directors at the time of such
nomination, or was elected or appointed by the affirmative vote of a majority of
such Continuing Directors.

          "Conversion Shares" shall mean any share of Original Common Stock
issued upon conversion of a share of Series B Common Stock in accordance with
the terms of the Series B Common Stock.

          "Exchange Act" shall mean the Securities and Exchange Act of 1934.

          "HSR Act" shall mean the Hart-Scott-Rodino Antitrust Improvements Act
of 1976, as amended.

          "Initial Shares" shall mean the shares of Series B Common Stock issued
pursuant to Section 1.1 of the Securities Purchase Agreement.

          "Net Payment Shares" shall mean the shares of Original Common Stock or
Series B Common Stock that are issued by the Company upon exercise of a Warrant
in accordance with Section 2(b) of the Warrant.

          "Net Payment Shares (Original)" shall mean the Net Payment Shares that
are shares of Original Common Stock.

          "Notice" has the meaning set forth in Section 7.4.

          "Occidental" shall mean Occidental Petroleum Corporation, a Delaware
corporation.

                              Appendix A - Page 2

<PAGE>

          "OCHC" shall mean Occidental Chemical Holding Corporation, a
California corporation.

          "Original Common Stock" shall mean all common stock, par value $1.00
per share, of the Company that is not Series B Common Stock.

          "Partner Sub Purchase Agreement" shall mean that certain Occidental
Partner Sub Purchase Agreement dated July 8, 2002 among the Company, OCHC,
Occidental Chemical Corporation and Oxy CH Corporation.

          "Party" shall mean the Company and the Stockholders.

          "Person" shall mean any individual, group, corporation, firm,
partnership, joint venture, trust, business association, organization,
governmental entity or other entity.

          "PIK Shares" shall mean any shares of Series B Common Stock issued at
the option of the Company, in lieu of a cash dividend otherwise required to be
paid, under the terms of the Series B Common Stock.

          "Pledge" has the meaning set forth in Section 4.1(d).

          "QIB" shall mean a "Qualified Institutional Buyer" as defined in Rule
144A of the Securities Act.

          "Registered Public Offering" has the meaning set forth in Section
4.1(b)(i).

          "Registration Rights Agreement" shall mean the Registration Rights
Agreement dated the date hereof among the Company and OCHC.

          "Related Securities Agreements" shall mean the Securities Purchase
Agreement, the Registration Rights Agreement and the Warrant.

          "Restructuring Transaction" shall mean any merger, consolidation or
recapitalization of the Company (or, if the capital stock of the Company is
affected, any Subsidiary of the Company), or any sale, lease, or other transfer
(in one transaction or a series of transactions contemplated or arranged by any
party as a single plan) of all or substantially all of the assets of the
Company.

          "SEC" shall mean the Securities and Exchange Commission.

          "Securities Act" shall mean the Securities Act of 1933, as amended,
and the rules and regulations thereunder.

          "Securities Purchase Agreement" has the meaning set forth in the
Recitals to this Agreement.

          "Series B Common Stock" shall mean the shares of Series B Common
Stock, par value $1.00 per share, of the Company.

                               Appendix A - Page 3

<PAGE>

          "Stockholder" shall mean (i) Occidental and OCHC, (ii) all Persons to
whom Subject Securities are Transferred that are required by the terms of this
Agreement to execute an adoption agreement and (iii) all Persons to whom Subject
Securities are Pledged that are required by the terms of this Agreement to
become a party to this Agreement, and, in each case, their respective
successors, permitted assigns, heirs, executors, trustees and administrators.

          "Subject Shares" shall mean the Initial Shares, Net Payment Shares,
Warrant Shares, PIK Shares, Contingent Shares and Conversion Shares, each until
sold pursuant to an effective registration statement or under Rule 144 of the
Securities Act.

          "Subject Securities" shall mean the Subject Shares and the Warrants.

          "Subsidiary" shall mean, with respect to any Party, any Person of
which such Party, either directly or indirectly, owns 50% or more of the equity
or voting interests.

          "Surviving Entity" shall mean an ultimate parent corporation or other
entity with a class of equity securities registered under Section 12 of the
Exchange Act and resulting from any Restructuring Transaction of the Company
where (x) the stockholders of the Company immediately prior to such
Restructuring Transaction beneficially own, immediately after such Restructuring
Transaction, directly or indirectly, shares or other ownership interests
representing in the aggregate more than 50% of (a) the then outstanding common
stock or other equity interests of the such Surviving Entity and (b) the
Combined Voting Power of the then outstanding Voting Securities of the Surviving
Entity or (y) the Continuing Directors at the time of the initial approval of
such Restructuring Transaction by the board of directors would immediately after
such Restructuring Transaction constitute a majority of the Board of Directors,
or similar managing group, of the Surviving Entity.

          "Termination Date" has the meaning set forth in Section 1.1.

          "Transfer" shall mean, with respect to any Subject Security, to
directly or indirectly (whether or not through an underwriter), offer, sell,
convey, distribute, transfer (by merger or otherwise), assign, devise, exchange,
encumber, gift, pledge, grant any option with respect to, hypothecate or
otherwise dispose of such Subject Security, or enter into any agreement,
arrangement or understanding with respect to the foregoing. Notwithstanding the
foregoing, as used herein, a "Transfer" shall not include any Transfer that
occurs by virtue of a Change of Control of Occidental.

          "Voting Securities" shall mean all securities of a corporation or
other entity having the right to vote in an election of the board of directors,
or similar managing group, of such corporation or other entity, whether at all
times or only so long as no senior class of securities of such corporation or
other entity has such voting power by reason of any contingency.

          "Warrant" shall mean the Warrants to purchase Original Common Stock of
the Company issued pursuant to the Securities Purchase Agreement.

          "Warrant Shares" shall mean the shares of Original Common Stock of the
Company issued upon exercise of the Warrant.

                              Appendix A - Page 4

<PAGE>

               "Wholly Owned Affiliate," with respect to any Party, shall mean
any Affiliate of such Party that is wholly owned, directly or indirectly, by
such Party's ultimate parent entity.

                               Appendix A - Page 5

<PAGE>

                                    EXHIBIT A

                         FORM OF COMPLIANCE CERTIFICATE

TO:       Lyondell Chemical Company
          1221 McKinney Street, Suite 700
          Houston, Texas 77010
          Attention: Gerald A. O'Brien
          Telecopy Number:  713-652-4538

FROM:     ____________________ (the "Stockholder")

DATE:     _______________, 20___

RE:       Transfer of Subject Securities pursuant to the Stockholders Agreement
          dated as of _________, 2002 among Lyondell Chemical Company, a
          Delaware corporation (the "Company"), and the Stockholders as defined
          therein (the "Stockholder Agreement").

          This compliance certificate (this "Certificate") is delivered to the
Company pursuant to Section 4.2(a) of the Stockholder Agreement. Capitalized
terms used herein but not defined herein have the meanings set forth in the
Stockholder Agreement.

          The undersigned Stockholder hereby represents and warrants that its
Transfer of Subject Securities was in compliance with Section 4.1(b) of the
Stockholder Agreement. Such Transfer consisted of:

     1.   Type and Number of Subject Securities:

          Warrant Shares: __________________________

          Conversion Shares: _______________________

          Net Payment Shares (Original): ___________

          Contingent Shares (Original): ____________

     2.   Nature of Transfer: (check one)

     !    pursuant to a Registered Public Offering;

     !    pursuant to Rule 144 of the Securities Act and the number of shares
          Transferred does not exceed the volume limitations set forth in Rule
          144(e) of the Securities Act (regardless of whether such volume
          limitations are applicable to the transferor stockholder); or

                                       A-1

<PAGE>

     !    a sale of not more than 15 million shares in a single transaction or
          series of transactions.

     3.   Transferee:

          ___________________________________________
          (name)

          ___________________________________________

          ___________________________________________

          ___________________________________________
          (address and contact information)

     4.   Date of Transfer:

          ______________, 20___

     5.   Status of Transferee:

          The Transferee ! is ! is not a QIB.

          Total number of shares of Common Stock beneficially owned, directly or
indirectly, by such Transferee after giving effect to this Transfer (required
only if the Transferee is not a QIB):

          ___________________________________________
          (Number includes Subject Shares and shares acquired in the open
market.)

          Accompanying this Certificate is the opinion of counsel required by
Section 4.4 of the Stockholder Agreement. Also attached hereto, if required by
Section 4.2 of the Stockholder Agreement, is a fully executed Adoption
Agreement.

          The undersigned Stockholder hereby requests that the Company transfer
the type and number of shares specified in paragraph 1 above upon its books.

[STOCKHOLDER]

By:_______________________
Name:
Title:

NOTE:     The above signature must correspond exactly with the name in the
          signature page of the Stockholder Agreement or in the Adoption
          Agreement attached hereto.

                                       A-2

<PAGE>

                                    EXHIBIT B

                           FORM OF ADOPTION AGREEMENT

          This Adoption Agreement ("Adoption") is executed pursuant to the terms
of the Stockholders Agreement dated as of ___________, 2002 among Lyondell
Chemical Company, a Delaware corporation (the "Company"), and the Stockholders
as defined therein (the "Stockholder Agreement"), by the transferee
("Transferee") and the ultimate parent entity of the Transferee ("Parent")
executing this Adoption. A copy of the Stockholder Agreement is attached hereto
and is incorporated herein by reference. Capitalized terms used herein but not
defined herein have the meanings set forth in the Stockholder Agreement.

          By the execution of this Adoption Agreement, Transferee and Parent
agree as follows:

     1.1  Transfer. Transferee is acquiring _______________ Subject Shares from
_________________[TRANSFEROR] on _______________, 20___ (the "Acquired Shares").

     1.2  Acknowledgment. Transferee and Parent acknowledge that (i) Transferee
is acquiring the Acquired Shares subject to the terms and conditions of the
Stockholder Agreement and (ii) Transferee and Parent beneficially own in the
aggregate, directly or indirectly, after giving effect to the acquisition of the
Acquired Shares, more than 5 million shares of Common Stock.

     1.3  Agreement. Transferee and Parent (i) agree that the Acquired Shares
acquired by Transferee, and any other securities of the Company, including
Subject Shares and shares of Original Common Stock purchased on the open market
that may be acquired by Transferee or Parent or their Subsidiaries in the
future, shall be bound by and subject to the terms of the Stockholder Agreement
in accordance with the terms thereof and (ii) hereby adopt the Stockholder
Agreement with the same force and effect as if they were originally parties
thereto and, effective as of the date hereof, are each a Stockholder as defined
therein.

     1.4  Representation. Transferee and Parent have the total number of shares
of Common Stock set forth next to their signature hereto.

     1.5  Notice. The address of Transferee and Parent for purposes of Section
7.4 of the Stockholder Agreement is as follows:

                                If to Transferee:

                                       _________________________
                                       _________________________
                                       _________________________
                                       _________________________
                                       Attention: ______________
                                       Telecopy Number: ________

                                      B-1

<PAGE>

                                       with a copy to:

                                       _________________________
                                       _________________________
                                       _________________________
                                       _________________________
                                       Attention: ______________
                                       Telecopy Number: ________

                                If to Parent:

                                       _________________________
                                       _________________________
                                       _________________________
                                       _________________________
                                       Attention: ______________
                                       Telecopy Number: ________

                                       with a copy to:

                                       _________________________
                                       _________________________
                                       _________________________
                                       _________________________
                                       Attention: ______________
                                       Telecopy Number: ________

                                       B-2

<PAGE>

                 IN WITNESS WHEREOF, this Adoption Agreement has been executed
on behalf of the undersigned by its officer thereunto duly authorized, effective
as of ___________, 20__.

<TABLE>
<CAPTION>
                                                                         Shares Beneficially Owned
                                                                           at Time of Execution
                                                             -------------------------------------------------
Stockholder (Transferee)                                                       Common Stock
-----------------------                                                        ------------
                                                                    (includes Subject Shares and shares
                                                                       purchased on the open market)
<S>                                                           <C>
[Name]

By:_________________________________________                 _________________________________________________
Name:
Title:

[Parent]

By _________________________________________                 _________________________________________________
Name:
Title:
</TABLE>

Note: The number of shares listed as beneficially owned by Parent does not
      include the shares beneficially owned by Transferee.

ACCEPTED AND AGREED to on behalf of the
Company and all Stockholders pursuant to
Section 7.16 of the Stockholder Agreement.

LYONDELL CHEMICAL COMPANY
(For itself and as Attorney-in-Fact for the Stockholders)

By: ____________________________________________
Name:
Title:

Date: _____________________ , 20___

                                       B-3

<PAGE>

                                   EXHIBIT C

              FORM OF ADOPTION AGREEMENT - WHOLLY OWNED AFFILIATES

                  This Adoption Agreement ("Adoption Agreement") is executed
pursuant to the terms of the Stockholders Agreement dated as of ___________,
2002 among Lyondell Chemical Company, a Delaware corporation (the "Company"),
and the Stockholders as defined therein (the "Stockholder Agreement"), by the
transferee ("Transferee") executing this Adoption Agreement. A copy of the
Stockholder Agreement is attached hereto and is incorporated herein by
reference. Capitalized terms used herein but not defined herein have the
meanings set forth in the Stockholder Agreement.

                  By the execution of this Adoption Agreement, the Transferee
agrees as follows:

         1.1      Type and Number of Shares.  Transferee is acquiring certain
Subject Securities of the Company as set forth below:

                  Subject Shares:

                           Original Common Stock:  _____________________________

                           Series B Common Stock: ______________________________

                  Warrants: ____________________________________________

                  Transferor: __________________________________________

                  Date of Transfer: ____________________________________

(the "Acquired Securities").

         1.2 Acknowledgment.  Transferee acknowledges that Transferee is
acquiring the Acquired Securities subject to the terms and conditions of the
Stockholder Agreement.

         1.3 Agreement. Transferee (i) agrees that the Subject Securities of the
Company, acquired by Transferee, and certain other securities of the Company
(including Subject Securities and shares of Original Common Stock purchased on
the open market) that may be acquired by the Transferee in the future, shall be
bound by and subject to the terms of the Stockholder Agreement pursuant to the
terms thereof and (ii) hereby adopts the Stockholder Agreement with the same
force and effect as if it were originally a party thereto and, effective as of
the date hereof, is a Stockholder as defined therein.

         1.4 Representation.  Transferee is a Wholly Owned Affiliate of a
Stockholder. Transferee beneficially owns in the aggregate, directly and
indirectly, the total number of Warrants and shares of Common Stock set forth
next to its signature hereto.

                                       C-1

<PAGE>

     1.5 Notice. The address of Transferee for purposes of Section 7.4 of the
Stockholder Agreement is as follows:

                             ______________________________________
                             ______________________________________
                             ______________________________________
                             ______________________________________
                             Attention: ___________________________
                             Telecopy Number: _____________________

                             with a copy to:

                             ______________________________________
                             ______________________________________
                             ______________________________________
                             ______________________________________
                             Attention: ___________________________
                             Telecopy Number: _____________________

                                       C-2

<PAGE>

                  IN WITNESS WHEREOF, this Adoption Agreement has been executed
on behalf of the undersigned by its officer thereunto duly authorized, effective
as of ___________, 20__.

<TABLE>
<CAPTION>
                                                             Shares and Warrants Beneficially Owned
                                                                      at Time of Execution
                                            -------------------------------------------------------------------------
                                                   Original                 Series B Common
Stockholder                                      Common Stock                    Stock                 Warrants
-----------                                 ------------------------     ---------------------    -------------------
<S>                                         <C>                          <C>                      <C>
                                               (includes Subject
                                               Shares and shares
                                             purchased on the open
                                                    market)

By: ___________________________________           __________                  __________              __________
Name:
Title:
</TABLE>

ACCEPTED AND AGREED to on behalf of the
Company and all Stockholders pursuant to
Section 7.16 of the Stockholder Agreement.

LYONDELL CHEMICAL COMPANY
(For itself and as Attorney-in-Fact for the Stockholders)

By: ________________________________________

Name:
Title:

Date: ______________________ , 20___

                                       C-3

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