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Exhibit 5.1

  XXX XXXXX XXXXX 000 XXXXXXXXX XXXXXXX, XXXXX 00000-4995   TEL x0 000.000.0000 FAX x0 000.000.0000 xxx.xxxxxxxxxx.xxx XXXXXX XXXXXX DUBAI HONG KONG HOUSTON LONDON MOSCOW NEW YORK RIYADH WASHINGTON

September 18, 2006

016119.0339

Lyondell Chemical Company

0000 XxXxxxxx Xxxxxx, Xxxxx 000

Houston, Texas 77010

Ladies and Gentlemen:

Lyondell Chemical Company, a Delaware corporation (the “Company”), and the subsidiary guarantors named in Schedule I hereto (the “Guarantors”), have engaged us to render the opinions we express below in connection with the Company’s offering of $875,000,000 of 8% Senior Unsecured Notes due 2014 (the “2014 Notes”), $900,000,000 of 8 ¹/4% Senior Unsecured Notes due 2016 (the “2016 Notes” and, together with the 2014 Notes, the “Notes”) and the issuance of the related guarantees of the Notes by the Guarantors (the “Guarantees” and, together with the Notes, the “Securities”), under the Registration Statement on Form S-3 (Reg. No. 333-137149) filed with the Securities and Exchange Commission (the “Commission”) under the Securities Act of 1933 (the “1933 Act”) by the Company and the Guarantors. The Registration Statement provides for the offering, issuance and sale from time to time of the securities described therein. At your request, this opinion is being furnished to you for filing on a Current Report on Form 8-K of the Company and incorporated by reference as Exhibit 5.1 to the Registration Statement.

In our capacity as your counsel in the connection referred to above, we have examined the following: (i) the Amended and Restated Certificate of Incorporation and Amended and Restated By-Laws of the Company, each as amended to date; (ii) the organizational documents of each of the Guarantors; and (iii) originals, or copies certified or otherwise identified, of corporate records of the Company and the Guarantors, certificates of public officials and of representatives of the Company and the Guarantors, statutes and other instruments and documents as a basis for the opinions hereafter expressed. We have relied upon certificates of officers of the Company and the Guarantors and of public officials with respect to the accuracy of the material factual matters contained in such certificates. We have assumed that the signatures on all documents examined by us are genuine, that all documents submitted to us as originals are accurate and complete, that all documents submitted to us as copies are true and correct copies of the originals thereof and that all information submitted to us was accurate and complete.

For purposes of the opinions we express below, we have also examined the following:

Lyondell Chemical Company 2 September 18, 2006

• the Registration Statement and its exhibits;

• the prospectus dated September 15, 2006 relating to the Registration Statement and filed with the SEC on September 18, 2006 pursuant to Rule 424(b)(5) of the 1933 Act (the “Prospectus”); and

• the Underwriting Agreement (the “Underwriting Agreement”) dated September 15, 2006 by and among the Company, the Guarantors and X.X. Xxxxxx Securities Inc., as representative of the several underwriters, relating to the offering and sale of the Notes.

In connection with this opinion, we have assumed that: (i) the 2014 Notes and the related Guarantees will be issued pursuant to an Indenture to be entered into among the Company, the Guarantors and The Bank of New York, as trustee, substantially in the form set forth as an exhibit to the Registration Statement and (ii) the 2016 Notes and the related Guarantees will be issued pursuant to an Indenture to be entered into among the Company, the Guarantors and The Bank of New York, as trustee, substantially in the form set forth as an exhibit to the Registration Statement. Each such Indenture is referred to herein as an “Indenture.”

On the basis of the foregoing, we are of the opinion that:

1. The Company is a corporation duly organized and validly existing in good standing under the laws of the State of Delaware.

2. When the Notes have been duly executed, authenticated and delivered in accordance with the provisions of the applicable Indenture and duly purchased and paid for in accordance with the terms of the Underwriting Agreement, (a) the Notes will constitute legal, valid and binding obligations of the Company, 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 constitute legal, valid and binding obligations of the Guarantors enforceable against the Guarantors 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 opinions set forth above are limited in all respects to matters of the General Corporation Law of the State of Delaware, the Revised Uniform Limited Partnership Act of the State of Delaware, the Limited Liability Company Act of the State of Delaware, the contract law of the State of New York and applicable federal law.

Lyondell Chemical Company 3 September 18, 2006

We hereby consent to the filing of this opinion of counsel as Exhibit 5.1 to the Current Report on Form 8-K of the Company dated September 15, 2006, to the incorporation by reference of this opinion of counsel into the Registration Statement and to the reference to our Firm under the heading “Legal Matters” in the Prospectus. 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 1933 Act or the rules and regulations of the Commission thereunder.

Very truly yours,

/s/ Xxxxx Xxxxx L.L.P.

Schedule I

GUARANTORS

Name		State of Organization
LRC Holdings GP LLC		Delaware
LRC Holdings LP LLC		Delaware
LRP Holdings LP LLC		Delaware
Lyondell Chemical Delaware Company		Delaware
Lyondell Chemical Nederland, Ltd.		Delaware
Lyondell Chemical Properties, L.P.		Delaware
Lyondell Chemical Technology 1 Inc.		Delaware
Lyondell Chemical Technology 2 Inc.		Delaware
Lyondell Chemical Technology 3 Inc.		Delaware
Lyondell Chemical Technology 4 Inc.		Delaware
Lyondell Chemical Technology 5 Inc.		Delaware
Lyondell Chemical Technology 6 Inc.		Delaware
Lyondell Chemical Technology 7 Inc.		Delaware
Lyondell Chemical Technology 8 Inc.		Delaware
Lyondell Chemical Technology, L.P.		Delaware
Lyondell Chemical Technology Management, Inc.		Delaware
Lyondell Chimie France Corporation		Delaware
LYONDELL-CITGO Refining LP		Delaware
Lyondell France, Inc.		Delaware
Lyondell Houston Refinery A Inc.		Delaware
Lyondell Houston Refinery Inc.		Delaware
Lyondell LP3 GP, LLC		Delaware
Lyondell LP3 Partners, LP		Delaware
Lyondell LP4 Inc.		Delaware
Lyondell (Pelican) Petrochemical L.P.1, Inc.		Delaware
Lyondell Petrochemical L.P. Inc.		Delaware
Lyondell Refining Company LP		Delaware
Lyondell Refining GP, LLC		Delaware
Lyondell Refining LP, LLC		Delaware
Lyondell Refining Partners, LP		Delaware
POSM Delaware, Inc.		Delaware
POSM II Properties Partnership, L.P.		Delaware