8-K

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

Current Report

Pursuant to Section

3 or 15(d) of the

Securities Exchange Act of 1934

Date of Report (date of earliest event reported): December 9, 2004

LYONDELL CHEMICAL COMPANY

(Exact name of registrant as specified in its charter)

Delaware

(State or other jurisdiction of incorporation)

1-10145 95-4160558

(Commission File Number) (I.R.S. Employer Identification No.)

1221 McKinney Street, Suite 700, Houston, Texas 77010

(Address of principal executive offices) (Zip Code)

(713) 652-7200

(Registrant's telephone number, including area code)

Not Applicable

(Former Name or Former Address, if Changed Since Last Report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions (see General Instruction A.2. below):

o Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

o Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

o Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

o Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Item 8.01 Other Events

Today, Lyondell Chemical Company ("Lyondell") announced that its Board of Directors has elected to convert Lyondell's outstanding shares of Series B Common Stock, held solely by Occidental Petroleum (through a subsidiary), to Common Stock on December 31, 2004.These shares will not be registered at the time of the conversion.

Lyondell's December 10, 2004 press release regarding this matter is filed with this Current Report on Form 8-K as Exhibit 99.1.

Item 9.01 Financial Statements and Exhibits

(c) Exhibits

1. Press Release

SIGNATURE

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

LYONDELL CHEMICAL COMPANY

By:/s/ Kerry A. Galvin

Name: Kerry A. Galvin

Title: Senior Vice President, General Counsel & Secretary

Date: December 10, 2004

INDEX TO EXHIBITS

Exhibit

Number Description

99.1 Press Release

EX-99.1

Exhibit 99.1

Contacts

Investors: Doug Pike, 713-309-4590

Media: Susan Moore, 713-652-4645

Lyondell Converts Series B Common Stock to Unregistered Common Stock

No Change in Total Common Stock Share Count

HOUSTON (December 10, 2004) -- Lyondell Chemical Company (NYSE: LYO) today announced that its Board of Directors has elected to convert the company's outstanding shares of Series B Common Stock, held solely by Occidental Petroleum (through a subsidiary), to Common Stock on December 31, 2004. These shares will not be registered at the time of the conversion.

Dividends on these newly converted shares will be paid in cash, avoiding dilution related to payment-in-kind dividends on shares of Series B Common Stock.

The conversion does not change the total number of outstanding shares which currently is approximately 242 million.

# # #

Lyondell Chemical Company, headquartered in Houston, Texas, is North America's third-largest independent, publicly traded chemical company. Lyondell is a major global manufacturer of basic chemicals and derivatives including ethylene, propylene, titanium dioxide, styrene, polyethylene, propylene oxide and acetyls. It also is a significant producer of gasoline blending components. The company has a 58.75 percent interest in LYONDELL-CITGO Refining LP, a refiner of heavy, high-sulfur crude oil. Lyondell is a global company operating on five continents and employs approximately 10,000 people worldwide.