December 30, 2005

Charles L. Hall, Vice President and Controller
Lyondell Chemical Company
1221 McKinney Street, Suite 700
Houston, Texas 77010

Re:	Lyondell Chemical Company 	File No. 001-10145
	Form 10-K for Fiscal Year Ended December 31, 2004
Form 10-Q for the Fiscal Quarters Ended September 30, 2005

Dear Mr. Hall:

      We have reviewed the above referenced filing and have the
following comments.  We have limited our review to the matters
addressed in the comments below.  We may ask you to provide us
with
supplemental information so we may better understand your
disclosure.
Please be as detailed as necessary in your explanation. Please
respond to these comments within 10 business days or tell us when
you
will provide us with a response.  Please submit all correspondence
and supplemental materials on EDGAR as required by Rule 101 of
Regulation S-T. Please understand that the purpose of our review
process is to assist you in your compliance with the applicable
disclosure requirements and to enhance the overall disclosure in
your
filing. We look forward to working with you in these respects. We
welcome any questions you may have about our comments or any other
aspect of our review.  Feel free to call us at the telephone
numbers
listed at the end of this letter.

Form 10-K for the Year Ended December 21, 2004

1. We note the disclosure in Note 11 about the $150 million
convertible debt obligation acquired in the 11/30/04 Millennium
merger. A supplemental indenture was simultaneously executed
giving
the debt holders the right to exchange the security for Lyondell
common stock at $13.63/share. Given Lyondell`s quoted stock price
at
this time, it appears that a beneficial conversion feature should
have been recognized in the financial statements. Please clarify
for
us whether this was considered in the purchase price allocation
for
the Millennium merger. Also, please provide us with your analysis
of
the appropriate accounting for subsequent changes in the fair
value
of the conversion feature. The guidance in EITF 00-19 and/or SFAS
133
may apply.


Form 10-Q for the Quarter Ended September 30, 2005

2. There is a concern that readers may have been surprised by the
magnitude of the $195 million TDI plant impairment charge. We note
the disclosure in prior filings about the "ongoing weak market
conditions" for TDI and the "lower product margins", high energy
and
raw material costs, and the deterioration in TDI operating results
since 2003.

However, we did not observe a disclosure about the material
uncertainty caused by these factors regarding Lyondell`s ability
to
recover the $195 million carrying value of TDI plant assets.
Section
501.02 of the Financial Reporting Codification contains guidance
on
the requirement for MD&A disclosure of uncertainties that could
materially impact future operating results. An uncertainty over
the
ability to recover a material amount of assets should be disclosed
unless management determines that the loss is "not reasonably
likely
to occur." It is not clear why the carrying value of assets at
risk
was not disclosed in MD&A of the June 30, 2005 10-Q given the
known
existence of certain adverse market and competitive factors that
contributed to the third quarter decision to permanently cease TDI
production at the plant. Please note for future filings.

	 We urge all persons who are responsible for the accuracy and
adequacy of the disclosure in the filing to be certain that the
filing includes all information required under the Securities
Exchange Act of 1934 and that they have provided all information
investors require for an informed investment decision.  Since the
company and its management are in possession of all facts relating
to
a company`s disclosure, they are responsible for the accuracy and
adequacy of the disclosures they have made. In connection with
responding to our comments, please provide, in writing, a
statement
from the company acknowledging that:

* the company is responsible for the adequacy and accuracy of the
disclosure in the filing;

* staff comments or changes to disclosure in response to staff
comments do not foreclose the Commission from taking any action
with
respect to the filing; and

* the company may not assert staff comments as a defense in any
proceeding initiated by the Commission or any person under the
federal securities laws of the United States.

      In addition, please be advised that the Division of
Enforcement
has access to all information you provide to the staff of the
Division of Corporation Finance in our review of your filing or in
response to our comments on your filing.


	You may contact Melissa Rocha at (202) 551-3854, Al Pavot at
(202) 551-3738 or me at (202) 551-3255 if you have any questions.

Sincerely,



Nili N. Shah
Branch Chief
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Charles L. Hall
December 30, 2005
Page 3 of 2


UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
WASHINGTON, D.C. 20549-7010

         DIVISION OF
   CORPORATION FINANCE