Opinion of Kerry A. Galvin

I am Senior Vice President, General Counsel and Secretary of Lyondell Chemical Company (the “Company”). This opinion is furnished to you in connection with the registration under the Securities Act of 1933, as amended, of 1,576,725 shares (the “Shares”) of common stock, par value $1.00 per share, of the Company (“Common Stock”) that may be issued under the Millennium Chemicals Inc. Long Term Stock Incentive Plan and Millennium Chemicals Inc. 2001 Omnibus Incentive Compensation Plan (the “Plans”). In such capacity, I am familiar with the Company’s Certificate of Incorporation and Bylaws, each as amended on or before the date hereof, as well as the Plans. In addition, I, or attorneys working under my supervision, have examined records of relevant corporate proceedings with respect to the offering of the Shares under the Plans and such other records, instruments and documents pertaining to the Company that I have deemed necessary for purposes of delivering this opinion. I have also examined the Company’s Registration Statement on Form S-8 to which this opinion is an exhibit (“Registration Statement”). I have assumed the genuineness of all signatures, the legal capacity of all natural persons, the authenticity of all documents examined as originals, the conformity to original documents of all documents examined as certified or photostatic copies and the authenticity of the originals of such copies.

Based on the foregoing and having regard for such legal considerations as I have deemed relevant, I am of the opinion that the Shares have been duly and validly authorized for issuance and, when issued in accordance with the terms of the Plans, will be duly and validly issued, fully paid and nonassessable.

The foregoing opinion is limited in all respects to matters governed by the General Corporation Law of the State of Delaware, which includes statutory provisions and also all applicable provisions of the Delaware Constitution and reported judicial decisions interpreting these laws, and the federal laws of the United States of America, to the extent applicable. I hereby consent to the filing of this opinion with the Securities and Exchange Commission as an exhibit to the Registration Statement.

Sincerely,

/S/ KERRY A. GALVIN

Kerry A. Galvin

Senior Vice President, General Counsel and Secretary