EXHIBIT 5

                        [Letterhead of Baker Botts LLP]


016119.0297

January 10, 2002

Lyondell Chemical Company
Lyondell Chemical Nederland, Ltd.
ARCO Chemical Technology, Inc.
ARCO Chemical Technology, LP
One Houston Center
1221 McKinney, Suite 700
Houston, Texas  77010

Ladies and Gentlemen:

          As set forth in the Registration Statement on Form S-4 (the
"Registration Statement") to be filed by Lyondell Chemical Company, a Delaware
corporation ("Lyondell"), Lyondell Chemical Nederland, Ltd., a Delaware
corporation ("LCNL"), ARCO Chemical Technology, Inc., a Delaware corporation
("ACTI"), and ARCO Chemical Technology, LP, a Delaware limited partnership
("ACTLP") (together, the "Co-registrants"), with the Securities and Exchange
Commission (the "Commission") under the Securities Act of 1933, as amended (the
"Act"), relating to the registration under the Act of $393 million aggregate
principal amount of 9 1/2% Senior Secured Notes due 2008 (the "New Notes") to be
offered by Lyondell in exchange (the "Exchange Offer") for a like principal
amount of its issued and outstanding 9 1/2% Senior Secured Notes due 2008 (the
"Outstanding Notes") and the issuance of the related guarantees of the New Notes
by LCNL, ACTI and ACTLP (the "Guarantees"), we are passing upon certain legal
matters in connection with the New Notes and the Guarantees for Lyondell, LCNL,
ACTI and ACTLP.  The New Notes are to be issued under an Indenture (the
"Indenture") dated as of December 4, 2001 among Lyondell, the Subsidiary
Guarantors party thereto and The Bank of New York, as trustee.  At your request,
this opinion is being furnished to you for filing as Exhibit 5 to the
Registration Statement.

          In our capacity as counsel to Lyondell, LCNL, ACTI and ACTLP in
connection with the matters referred to above, we have examined the following:
(i) the Amended and Restated Certificate of Incorporation and the Amended and
Restated Bylaws of Lyondell, the Certificate of Incorporation and Bylaws of
LCNL, the Certificate of Incorporation and the Bylaws of ACTI, and the
Certificate of Limited Partnership and Partnership Agreement of ACTLP, each as
amended to date, (ii) the Indenture and (iii) the originals, or copies certified
or otherwise identified, of corporate records of Lyondell, LCNL, ACTI and ACTLP,
including minute books of Lyondell, LCNL, ACTI and ACTLP as furnished to us by
Lyondell, LCNL, ACTI and ACTLP, certificates of public officials and of
representatives of Lyondell, LCNL, ACTI and ACTLP, statutes and other
instruments and documents as a basis for the opinions hereinafter expressed.  In
giving such an opinion, we have relied upon certificates of officers of
Lyondell, LCNL, ACTI and ACTLP with respect to the accuracy of the material
factual matters


BAKER BOTTS LLP

Lyondell Chemical Company
Lyondell Chemical Nederland, Ltd.
ARCO Chemical Technology, Inc.
ARCO Chemical Technology, LP
January 10, 2002
Page 2

contained in such certificates. We have assumed that all signatures on documents
examined by us are genuine, all documents submitted to us are authentic and all
documents submitted as certified or photostatic copies conform to the originals
thereof.

          On the basis of the foregoing, and subject to the assumptions,
limitations and qualifications set forth herein, we are of the opinion that when
(i) the Registration Statement has become effective under the Act and the
Indenture has been qualified under the Trust Indenture Act of 1939, as amended,
and (ii) the New Notes have been duly executed, authenticated and delivered in
accordance with the provisions of the Indenture and issued in exchange for
Outstanding Notes pursuant to, and in accordance with the terms of, the Exchange
Offer as contemplated in the Registration Statement, (a) the New Notes will
constitute legal, valid and binding obligations of Lyondell, enforceable against
it in accordance with their terms, except to the extent that the enforceability
thereof may be limited by bankruptcy, fraudulent conveyance, insolvency,
reorganization, moratorium or other laws relating to or affecting creditors'
rights generally and by general principles of equity and public policy
(regardless of whether such enforceability is considered in a proceeding in
equity or at law) and (b) the Guarantees will be entitled to the benefits of the
Indenture and will constitute legal, valid and binding obligations of LCNL, ACTI
and ACTLP enforceable against LCNL, ACTI and ACTLP in accordance with their
terms, except to the extent that the enforceability thereof may be limited by
bankruptcy, fraudulent conveyance, insolvency, reorganization, moratorium or
other laws relating to or affecting creditors' rights generally and by
principles of equity (regardless of whether such enforceability is considered in
a proceeding in equity or at law).

          The opinion set forth above is based on and limited in all respects to
matters of the federal laws of the United States, the General Corporation Law of
the State of Delaware, the Revised Uniform Limited Partnership Act of the State
of Delaware, the contract law of the State of New York and the laws of the State
of Texas, each as currently in effect.

          We hereby consent to the filing of this opinion of counsel as Exhibit
5 to the Registration Statement and to the reference to our Firm under the
heading "Legal Matters" in the prospectus forming a part of the Registration
Statement.  In giving this consent, we do not hereby admit that we are in the
category of persons whose consent is required under Section 7 of the Act or the
rules and regulations of the Commission thereunder.


                              Very truly yours,

                              BAKER BOTTS L.L.P.

SAM/SA