<PAGE>

    As filed with the Securities and Exchange Commission on October 22, 2002

                                                    Registration No. 333-_______

================================================================================

                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

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

                                    FORM S-8
                             REGISTRATION STATEMENT
                                      Under
                           THE SECURITIES ACT OF 1933

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

                            LYONDELL CHEMICAL COMPANY
             (Exact Name of Registrant as Specified in Its Charter)

<TABLE>
   <S>                               <C>                                                    <C>
                                              1221 McKinney Street, Suite 700
              Delaware                              Houston, Texas 77010                       95-4160558
   (State or Other Jurisdiction of                                                           (I.R.S. Employer
   Incorporation or Organization)    (Address of Principal Executive Offices and Zip Code)  Identification No.)
</TABLE>

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

                            LYONDELL CHEMICAL COMPANY
                          1999 LONG-TERM INCENTIVE PLAN

                            (Full Title of the Plan)

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

                                 KERRY A. GALVIN
              Senior Vice President, General Counsel and Secretary
                            Lyondell Chemical Company
                        1221 McKinney Street, Suite 700
                             Houston, Texas 77010
                     (Name and Address of Agent for Service)

                                 (713) 652-7200
                     (Telephone Number, Including Area Code,
                              of Agent for Service)

                         CALCULATION OF REGISTRATION FEE
<TABLE>
<CAPTION>
---------------------------------------------------------------------------------------------------------------------

                                                                Proposed maximum   Proposed maximum      Amount
    Title of securities to be registered        Amount to be     offering price   aggregate offering of Registration
                                                 registered      per share (2)         price (2)         Fee (2)
---------------------------------------------------------------------------------------------------------------------
<S>                                             <C>             <C>               <C>                <C>
 Common Stock, par value $1.00 per share (1) ..  4,000,000           $12.85           $51,400,000        $4,729
---------------------------------------------------------------------------------------------------------------------
</TABLE>

(1)  Includes the associated rights to purchase Common Stock, which initially
     are attached to and trade with the shares of Common Stock registered
     hereby.
(2)  Estimated pursuant to Rule 457(c) and (h) solely for the purpose of
     computing the registration fee and based upon the average of the high and
     low sales price of the Common Stock of the Registrant reported on the New
     York Stock Exchange on October 17, 2002.

================================================================================

<PAGE>

                                     PART I

              INFORMATION REQUIRED IN THE SECTION 10(A) PROSPECTUS

        Note: The document(s) containing the employee benefit plan information
required by Item 1 of Form S-8 and the statement of availability of information
about us and any other information required by Item 2 of Form S-8 will be sent
or given to participants as specified by Rule 428 under the Securities Act of
1933, as amended (the "Securities Act"). In accordance with Rule 428 and the
requirements of Part I of Form S-8, such documents are not being filed with the
Securities and Exchange Commission (the "Commission") either as part of this
Registration Statement or as prospectuses or prospectus supplements pursuant to
Rule 424 under the Securities Act. We shall maintain a file of such documents in
accordance with the provisions of Rule 428. Upon request, we will furnish to the
Commission or its staff a copy or copies of all of the documents included in
such file.

                                     PART II

               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

Item 3. Incorporation of Documents by Reference.

        We file annual, quarterly and current reports, proxy statements and
other information with the SEC. You can read and copy any materials we file with
the SEC at the SEC's public reference room at 450 Fifth Street, N.W.,
Washington, D.C. 20549. You can obtain information about the operation of the
SEC's public reference room by calling the SEC at 1-800-SEC-0330. The SEC also
maintains a web site that contains information we file electronically with the
SEC, which you can access over the Internet at http://www.sec.gov, and our
electronic SEC filings are also available from our web site at www.lyondell.com.
Information contained on our web site or any other web site is not incorporated
into this Registration Statement and does not constitute a part of this
Registration Statement. You can also obtain information about us at the offices
of the New York Stock Exchange, 20 Broad Street, New York, New York 10005.

        The SEC allows us to incorporate by reference the information we file
with it, which means we can disclose important information to you by referring
you to those documents. The information we incorporate by reference is an
important part of this Registration Statement, and later information we file
with the SEC will automatically update and supersede that information. We
incorporate by reference the documents listed below, and any future filings we
make with the SEC under Section 13(a), 13(c), 14 or 15(d) of the Securities
Exchange Act of 1934 until we sell all the offered securities. The documents we
incorporate by reference are:

        .  our annual report on Form 10-K for the year ended December 31, 2001;

        .  our quarterly reports on Form 10-Q for the quarters ended March 31,
           2002, and June 30, 2002;

        .  our current reports on Form 8-K filed on January 11, 2002, June 21,
           2002, June 28, 2002, July 9, 2002, September 6, 2002 and October 22,
           2002; and

        .  the description of our Common Stock (including the related rights)
           contained in our Current Report on Form 8-K filed October 22, 2002,
           as such may be amended from time to time.

Item 4. Description of Securities.

        Not Applicable.

Item 5. Interest of Named Experts and Counsel.

        The legality of the Common Stock is opined on by Kerry A. Galvin, our
Senior Vice President and General Counsel. As of September 30, 2002, Ms. Galvin
owned 7,084 shares of Common Stock, either directly or through employee benefit
plans, and held options to acquire 280,260 shares of Common Stock.

                                       II-1

<PAGE>

Item 6. Indemnification of Directors and Officers.

Delaware General Corporation Law

        Section 102(b)(7) of the Delaware General Corporation Law permits a
corporation to provide in its certificate of incorporation that a director of
the corporation shall not be personally liable to the corporation or its
stockholders for monetary damages for breach of fiduciary duty as a director,
except for liability for any of the following:

        .  any breach of the director's duty of loyalty to the corporation or
           its stockholders,

        .  acts or omissions not in good faith or which involve intentional
           misconduct or a knowing violation of law,

        .  payments of unlawful dividends or unlawful stock repurchases or
           redemptions, or

        .  any transaction from which the director derived an improper personal
           benefit.

        Any repeal or modification of such provisions shall not adversely affect
any right or protection of a director for or with respect to any acts or
omissions of such director occurring prior to such amendment or repeal. Our
Amended and Restated Certificate of Incorporation provides that no director
shall be personally liable to us or any of our stockholders for monetary damages
for breach of fiduciary duty as a director to the fullest extent permitted by
Delaware law.

        Under Section 145 of the Delaware General Corporation Law, a corporation
may indemnify any individual made a party or threatened to be made a party to
any type of proceeding, other than an action by or in the right of the
corporation, because he or she is or was an officer, director, employee or agent
of the corporation or was serving at the request of the corporation as an
officer, director, employee or agent of another corporation or entity against
expenses, judgments, fines and amounts paid in settlement actually and
reasonably incurred in connection with such proceeding: (1) if he or she acted
in good faith and in a manner he or she reasonably believed to be in or not
opposed to the best interests of the corporation; or (2) in the case of a
criminal proceeding, he or she had no reasonable cause to believe that his or
her conduct was unlawful. A corporation may indemnify any individual made a
party or threatened to be made a party to any threatened, pending or completed
action or suit brought by or in the right of the corporation because he or she
was an officer, director, employee or agent of the corporation, or is or was
serving at the request of the corporation as a director, officer, employee or
agent of another corporation or other entity, against expenses actually and
reasonably incurred in connection with such action or suit if he or she acted in
good faith and in a manner he or she reasonably believed to be in or not opposed
to the best interests of the corporation, provided that such indemnification
will be denied if the individual is found liable to the corporation unless, in
such a case, the court determines the person is nonetheless entitled to
indemnification for such expenses. A corporation must indemnify a present or
former director or officer who successfully defends himself or herself in a
proceeding to which he or she was a party because he or she was a director or
officer of the corporation against expenses actually and reasonably incurred by
him or her. Expenses incurred by an officer or director, or any employees or
agents as deemed appropriate by the board of directors, in defending civil or
criminal proceedings may be paid by the corporation in advance of the final
disposition of such proceedings upon receipt of an undertaking by or on behalf
of such director, officer, employee or agent to repay such amount if it shall
ultimately be determined that he or she is not entitled to be indemnified by the
corporation. The Delaware law regarding indemnification and expense advancement
is not exclusive of any other rights which may be granted by our certificate of
incorporation or bylaws, a vote of stockholders or disinterested directors,
agreement or otherwise.

Bylaws

        Our Amended and Restated Bylaws ("Bylaws") contain indemnification
rights for our directors and our officers. Specifically, the Bylaws provide that
we shall indemnify our officers and directors with respect to all matters to
which Section 145 of the Delaware General Corporation Law may in any way relate,
to the fullest extent permitted or allowed by the laws of the State of Delaware.
Further, we may maintain insurance to protect us and any of our directors and
officers or directors or officers of another corporation, partnership, joint
venture, trust or other enterprise against expense, liability or loss. We may
also enter into indemnity agreements with persons who are members of our Board
of Directors, our elected officers and with other persons as the Board of
Directors may designate.

                                       II-2

<PAGE>

Indemnity Agreements

     We have entered or will enter into indemnity agreements ("Indemnity
Agreements") with each of our present and future directors and officers
(individually, the "Indemnitee" and collectively, the "Indemnitees"). Each
provides for the indemnification of and the advancing of expenses to the
Indemnitee to the fullest extent permitted by Delaware law. More specifically,
each Indemnity Agreement provides (i) that an Indemnitee is automatically
entitled to indemnification for expenses to the extent an Indemnitee (including
the Indemnitee's estate, heirs, executors, and administrators) is successful in
defending any indemnifiable claim whether on the merits or otherwise, (ii) that
an Indemnitee is entitled to the advancement of expenses during the pendency of
a proceeding, (iii) that we have the burden of proving that an Indemnitee is not
entitled to indemnification and negates certain presumptions that may otherwise
be drawn against an Indemnitee, (iv) a mechanism through which an Indemnitee may
seek court relief in the event the Reviewing Party (as defined in the Indemnity
Agreements) determines that the Indemnitee would not be entitled to be
indemnified, (v) that an Indemnitee is entitled to indemnification against all
expenses (including attorneys' fees) incurred in seeking to collect an indemnity
claim or advancement of expenses from us and (vi) that after there has been a
Change of Control (as defined in the Indemnity Agreements), all of our
determinations regarding a right to indemnity, and the right to advancement of
expenses, shall be made by independent legal counsel.

     In the event of a Potential Change in Control (as defined in the Indemnity
Agreements), the Indemnity Agreements require us, upon written request of the
Indemnitee, to create a trust to indemnify the Indemnitee and to fund such trust
in an amount sufficient to cover expenses reasonably anticipated. Upon a Change
of Control, the trust would become irrevocable and the funds committed to such
trust would not be available to us for use as working capital. All unexpended
funds in the trust will revert to us upon a final court determination that an
Indemnitee has been fully indemnified under the terms of the Indemnity
Agreement.

     Indemnitees' rights under the Indemnity Agreements are not exclusive of any
other rights they may have under Delaware Law, directors' and officers'
liability insurance, our Bylaws or otherwise. However, the Indemnity Agreements
do prevent double payment.

     If, in the future, because of changes in Delaware Law or otherwise, we
determine that the Indemnity Agreements do not provide indemnification to the
fullest extent of the Delaware law, we intend to amend such agreements, or enter
into new agreements with directors and officers, to provide, in our judgment,
for full indemnification.

     We believe that the Bylaws and the Indemnity Agreements are largely
confirmatory of Delaware law. However, the provisions of the Bylaws and the
Indemnity Agreements apply to proceedings arising from acts or omissions
occurring before or after their respective adoption or execution. In addition,
the contract right explicitly created in the Indemnity Agreements gives the
Indemnitee protection against a subsequent, adverse change in the
indemnification provisions of our Bylaws, such as might occur in the event of a
Change of Control (as defined in the Indemnity Agreements). Upon a Change of
Control, the establishment of a trust fund pursuant to the Indemnity Agreements
might facilitate indemnification payments, but would not broaden the rights to
indemnity thereunder. Furthermore, under the Delaware Law, the advance of
litigation expenses is discretionary; under the Indemnity Agreements, such
advance is mandatory absent a special determination to the contrary. Litigation
expenses incurred by an Indemnitee in a proceeding to seek recovery of amounts
due under the Indemnity Agreement are recoverable under the Indemnity Agreement
if the Indemnitee is successful in whole or in part. In the absence of the
Indemnity Agreement, such expenses might not have been recoverable.

     Unlike Delaware law, which authorizes the payment of expenses (including
legal fees) in a stockholders' derivative suit, but not of any other amounts,
such as fees or settlements, the Indemnity Agreements do not distinguish between
indemnification for claims brought by or in the right of Lyondell Chemical
Company and indemnification for claims brought by third parties. Accordingly, we
would be permitted under an Indemnity Agreement to indemnify an Indemnitee
within the limits established by law and public policy.

Long Term Incentive Plan

     In addition, Section 3 of the Lyondell Chemical Company 1999 Long-Term
Incentive Plan (the "Plan") provides that no Committee member and none of our
officers to whom the Committee has delegated authority according to the Plan
shall be liable for anything done by him or her or omitted to be done while
performing any Plan duties, except for his or her own willful misconduct or as
expressly provided by statute.

                                       II-3

<PAGE>

     The above discussion of the Delaware General Corporation Law, our Amended
and Restated Certificate of Incorporation, Bylaws, Indemnity Agreements, and the
Plan is intended to be only a summary and is qualified in its entirety by the
full text of each of the foregoing.

Item 7. Exemption from Registration Claimed.

        Not applicable.

Item 8. Exhibits

        The following documents are filed as a part of this registration
statement or incorporated by reference herein:

Exhibit
  No.                                  Description
-------                                -----------

4.1*    --   Amended and Restated Certificate of Incorporation of Lyondell
             Chemical Company (incorporated herein by this reference to Exhibit
             4.1 to our Current Report on Form 8-K filed October 22, 2002)

4.2*    --   Amended and Restated Bylaws of Lyondell Chemical Company
             (incorporated herein by this reference to Exhibit 3.2 of our
             Annual Report on Form 10-K for the year ended December 31, 2001)

4.3*    --   Rights Agreement between Lyondell Chemical Company and The Bank
             of New York, as Rights Agent (incorporated herein by this
             reference to Exhibit 1 of our Current Report on Form 8-K filed
             December 12, 1995)

4.4*    --   Amendment to Rights Agreement between Lyondell Chemical Company
             and The Bank of New York, as Rights Agent (incorporated herein by
             this reference to Exhibit 4.4 of our Current Report on Form 8-K
             filed September 6, 2002)

4.5     --   Lyondell Chemical Company 1999 Long-Term Incentive Plan, as
             amended and restated effective January 1, 2002 (filed herewith)

5       --   Opinion of Kerry A. Galvin, Senior Vice President, General Counsel
             and Secretary of the Company (filed herewith)

23.1    --   Consent of Kerry A. Galvin (included in Exhibit 5)

23.2    --   Consent of PricewaterhouseCoopers LLP (filed herewith)

24      --   Powers of Attorney (filed herewith)

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

* Incorporated herein by reference as indicated.

Item 9. Undertakings.

         (a) The undersigned registrant hereby undertakes:

         (1) To file, during any period in which offers or sales are being made,
         a post-effective amendment to this Registration Statement:

                    (i)  To include any prospectus required by section 10(a)(3)
               of the Securities Act;

                    (ii) To reflect in the prospectus any facts or events
               arising after the effective date of the Registration Statement
               (or the most recent post-effective amendment thereof) which,
               individually or in the aggregate, represent a fundamental change
               in the information set forth in

                                       II-4

<PAGE>

               the Registration Statement. Notwithstanding the foregoing, and
               increase or decrease in volume of securities offered (if the
               total dollar value of securities offered would not exceed that
               which was registered) and any deviation from the low or high end
               of the estimated maximum offering range may be reflected in the
               form of prospectus filed with the Commission pursuant to Rule
               424(b) of the Securities Act if, in the aggregate, the changes in
               volume and price represent no more than a 20% change in the
               maximum aggregate offering price set forth in the "Calculation of
               Registration Fee" table in the effective Registration Statement;

                    (iii) To include any material information with respect to
               the plan of distribution not previously disclosed in the
               Registration Statement or any material change to such information
               in the Registration Statement;

          provided, however, that paragraphs (a)(1)(i) and (a)(1)(ii) do not
          apply if the Registration Statement is on Form S-3 or Form S-8, and
          the information required to be included in a post-effective amendment
          by those paragraphs is contained in periodic reports filed with or
          furnished to the Commission by the registrant pursuant to Section 13
          or 15(d) of the Exchange Act that are incorporated by reference in the
          Registration Statement.

          (2) That, for the purpose of determining any liability under the
          Securities Act, each such post-effective amendment shall be deemed to
          be a new registration statement relating to the securities offered
          therein, and the offering of such securities at that time shall be
          deemed to be the initial bona fide offering thereof.

          (3) To remove from registration by means of a post-effective amendment
          any of the securities being registered which remain unsold at the
          termination of the offering.

          (b) The undersigned registrant hereby undertakes that, for purposes of
determining any liability under the Securities Act, each filing of the
registrant's annual report pursuant to Section 13(a) or 15(d) of the Exchange
Act (and, where applicable, each filing of an employee benefit plan's annual
report pursuant to Section 15(d) of the Exchange Act) that is incorporated by
reference in the Registration Statement shall be deemed to be a new registration
statement relating to the securities offered therein, and the offering of such
securities at that time shall be deemed to be the initial bona fide offering
thereof.

          (c) Insofar as indemnification for liabilities arising under the
Securities Act may be permitted to directors, officers and controlling persons
of the registrant pursuant to the foregoing provisions, or otherwise, the
registrant has been advised that in the opinion of the Commission such
indemnification is against public policy as expressed in the Securities Act and
is, therefore, unenforceable. In the event that a claim for indemnification
against such liabilities (other than the payment by the registrant of expenses
incurred or paid by a director, officer or controlling person of the registrant
in the successful defense of any action, suit or proceeding) is asserted by such
director, officer or controlling person in connection with the securities being
registered, the registrant will, unless in the opinion of its counsel the matter
has been settled by controlling precedent, submit to a court of appropriate
jurisdiction the question whether such indemnification by it is against public
policy as expressed in the Securities Act and will be governed by the final
adjudication of such issue.

                                       II-5

<PAGE>

                                   SIGNATURES

     Pursuant to the requirements of the Securities Act, the registrant
certifies that it has reasonable grounds to believe that it meets all of the
requirements for filing on Form S-8 and has duly caused this Registration
Statement on Form S-8 to be signed on its behalf by the undersigned, thereunto
duly authorized, in the city of Houston, state of Texas, on this 22nd day of
October, 2002.

                                LYONDELL CHEMICAL COMPANY


                               By: /s/ Kerry A. Galvin
                                   --------------------------------------------
                                   Name:  Kerry A. Galvin
                                   Title: Senior Vice President, General Counsel
                                          and Secretary

     Pursuant to the requirements of the Securities Act of 1933, this
Registration Statement on Form S-8 has been signed by the following persons in
the capacities and on the date indicated.

<TABLE>
<S>                                                     <C>                               <C>
                        *                               Chairman of the Board             October 22, 2002
---------------------------------------------------
              Dr. William T. Butler

                        *                               President, Chief Executive        October 22, 2002
---------------------------------------------------
                  Dan F. Smith                          Officer and Director
          (Principal Executive Officer)

                        *                               Director                          October 22, 2002
---------------------------------------------------
                Carol A. Anderson

                        *                               Director                          October 22, 2002
---------------------------------------------------
                  Travis Engen

                        *                               Director                          October 22, 2002
---------------------------------------------------
           Stephen F. Hinchliffe, Jr.

                        *                               Director                          October 22, 2002
---------------------------------------------------
                 David J. Lesar

                        *                               Director                          October 22, 2002
---------------------------------------------------
               Dudley C. Mecum II

                        *                               Director                          October 22, 2002
---------------------------------------------------
             Dr. William R. Spivey

                        *                               Director                          October 22, 2002
---------------------------------------------------
                Dr. Ray R. Irani

                        *                               Director                          October 22, 2002
---------------------------------------------------
                Stephen I. Chazen


                        *                               Senior Vice President and         October 22, 2002
---------------------------------------------------
                T. Kevin DeNicola                       Chief Financial Officer
          (Principal Financial Officer)

                        *                                                                 October 22, 2002
---------------------------------------------------
                 Charles L. Hall                        Vice President and Controller
         (Principal Accounting Officer)

*By: /s/ Kerry A. Galvin
     ----------------------------------------------
      Kerry A. Galvin, as Attorney in fact
</TABLE>

                                       II-6

<PAGE>

                                  EXHIBIT INDEX

Exhibit
  No.                                   Description
-------                                 -----------

4.1*    --   Amended and Restated Certificate of Incorporation of Lyondell
             Chemical Company (incorporated herein by this reference to Exhibit
             4.1 to our Current Report on Form 8-K filed October 22, 2002)

4.2*    --   Amended and Restated Bylaws of Lyondell Chemical Company
             (incorporated herein by this reference to Exhibit 3.2 of our Annual
             Report on Form 10-K for the year ended December 31, 2001)

4.3*    --   Rights Agreement between Lyondell Chemical Company and The Bank
             of New York, as Rights Agent (incorporated herein by this reference
             to Exhibit 1 of our Current Report on Form 8-K filed December 12,
             1995)

4.4*    --   Amendment to Rights Agreement between Lyondell Chemical Company and
             The Bank of New York, as Rights Agent (incorporated herein by this
             reference to Exhibit 4.4 of our Current Report on Form 8-K filed
             September 6, 2002)

4.5     --   Lyondell  Chemical Company 1999 Long-Term Incentive Plan, as
             amended and restated effective January 1, 2002 (filed herewith)

5       --   Opinion of Kerry A. Galvin, Senior Vice President, General counsel
             and Secretary of the Company (filed herewith)

23.1    --   Consent of Kerry A. Galvin (included in Exhibit 5)

23.2    --   Consent of PricewaterhouseCoopers LLP (filed herewith)

24      --   Powers of Attorney (filed herewith)

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

* Incorporated herein by reference as indicated.