Filed by Lyondell Chemical Company

Pursuant to Rule 425 under the Securities Act of 1933 and

Deemed Filed Pursuant to Rule 14a-12 under the Securities Exchange Act of 1934

Form S-4 Registration Statement File No.: 333-114877

Subject Company: Millennium Chemicals Inc.

Additional Information:

On June 18, 2004, Lyondell Chemical Company (“Lyondell”) filed with the Securities and Exchange Commission (the “SEC”) an amendment to its registration statement on Form S-4 (as amended, the “Form S-4”) containing a preliminary joint proxy statement/prospectus regarding the proposed transaction between Lyondell and Millennium Chemicals Inc. (“Millennium”). Investors and security holders are urged to read that document and any other relevant documents filed or that will be filed with the SEC, including the definitive joint proxy statement/prospectus that will be part of the definitive registration statement, as they become available, because they contain, or will contain, important information. Investors and security holders may obtain a free copy of the definitive joint proxy statement/prospectus (when it becomes available) and other documents filed by Lyondell and Millennium with the SEC at the SEC’s web site at www.sec.gov. The definitive joint proxy statement/prospectus (when it becomes available) and the other documents filed by Lyondell may also be obtained free from Lyondell by calling Lyondell’s Investor Relations department at (713) 309-4590.

The respective executive officers and directors of Lyondell and Millennium and other persons may be deemed to be participants in the solicitation of proxies in respect of the proposed transaction. Information regarding Lyondell’s executive officers and directors is available in the proxy statement filed with the SEC by Lyondell on March 16, 2004 and in the Form S-4, and information regarding Millennium’s directors and its executive officers is available in Millennium’s Annual Report on Form 10-K/A for the year ended December 31, 2003, which was filed with the SEC on April 27, 2004, and in the Form S-4. Other information regarding the participants in the proxy solicitation and a description of their direct and indirect interests, by security holdings or otherwise, will be contained in the definitive joint proxy statement/prospectus and other relevant materials filed with the SEC, as they become available.

Forward-Looking Statements:

This release contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. Such statements include, but are not limited to, statements about the benefits of the proposed transaction between Lyondell and Millennium, including financial and operating results, Lyondell’s plans, objectives, expectations and intentions and other statements that are not historical facts. Such statements are based upon the current beliefs and expectations of Lyondell’s management and are subject to significant risks and uncertainties. Actual results may differ materially from those set forth in the forward-looking statements. The following factors, among others, could affect the proposed transaction and the anticipated results: approval by Lyondell’s and Millennium’s respective shareholders, amendments to Lyondell’s and Millennium’s respective credit facilities and the parties’ ability to achieve expected synergies in the transaction within the expected timeframes or at all. Additional factors that could cause Lyondell’s results to differ materially from those described in the forward-looking statements can be found in Lyondell’s Annual Report on Form 10-K for the year ended December 31, 2003, which was filed with the SEC on March 12, 2004, and Lyondell’s Quarterly Report on Form 10-Q for the quarter ended March 31, 2004, which was filed with the SEC on May 7, 2004.

This filing contains the text of an announcement sent to all employees of Lyondell or Equistar Chemicals, LP (a joint venture owned 70.5% by Lyondell) on July 8, 2004. These materials are being filed pursuant to Rule 425 under the Securities Act of 1933.

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Announcement:

Date:	July 8, 2004
From:	Bart de Jong
To:	All Employees
Subject:	Additional Planned Leadership of TiO2 Support Organizations

Today I am pleased to announce additional planned leadership assignments for two functions that will support the TiO₂ business after the closing of our proposed transaction with Millennium.

Upon the close of the transaction it is anticipated that Corey Siegel will continue in his position as Vice President, Tax, Millennium. Corey will report to Allen Holmes, Vice President, Tax and Real Estate, Lyondell, to ensure that the tax activities of the two organizations are appropriately coordinated. Corey and his organization will have primary responsibility for the tax planning and tax audit functions of Millennium, including support for the TiO₂ business. The Millennium tax audit function will remain in Red Bank, New Jersey, and will have primary responsibility for the tax audits relating to all tax years through the close. The Millennium tax reporting and compliance functions in Hunt Valley, Maryland, will remain in place for such time as is necessary to substantially complete the necessary governmental filings for all years through the close. Thereafter, the Hunt Valley tax reporting and compliance functions will be integrated into and relocated to Houston.

Bill McEnroe will become Regional Manager, HSE, TiO₂, and will have primary responsibility for the support of Health, Safety and Environment (HSE) for the TiO₂ business. Bill will report to Karen Swindler, GM & Divisional VP, Responsible Care, Lyondell, with a dotted line reporting relationship to Brian Goedke when he becomes Vice President of the global Manufacturing organization for TiO₂ at the time of closing. Overall HSE direction and strategy will continue to be provided from Houston.

These materials contain forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. Such statements include, but are not limited to, statements about the benefits of the proposed transaction between Lyondell Chemical Company (“Lyondell”) and Millennium Chemicals Inc. (“Millennium”), including financial and operating results, Lyondell’s plans, objectives, expectations and intentions and other statements that are not historical facts. Such statements are based upon the current beliefs and expectations of Lyondell’s management and are subject to significant risks and uncertainties. Actual results may differ materially from those set forth in the forward-looking statements. The following factors, among others, could affect the proposed transaction and the anticipated results: approval by Lyondell’s and Millennium’s respective shareholders, amendments to Lyondell’s and Millennium’s respective credit facilities and the parties’ ability to achieve expected synergies in the transaction within the expected timeframes or at all. Additional factors that could cause Lyondell’s results to differ materially from those described in the forward-looking statements can be found in Lyondell’s Annual Report on Form 10-K for the year ended December 31, 2003, which was filed with the Securities and Exchange

Commission (the “SEC”) on March 12, 2004, and Lyondell’s Quarterly Report on Form 10-Q for the quarter ended March 31, 2004, which was filed with the SEC on May 7, 2004.

In addition, on June 18, 2004, Lyondell filed with the SEC an amendment to its registration statement on Form S-4 (as amended, the “Form S-4”) containing a preliminary joint proxy statement/prospectus regarding the proposed transaction between Lyondell and Millennium. Investors and security holders are urged to read that document and any other relevant documents filed or that will be filed with the SEC, including the definitive joint proxy statement/prospectus that will be part of the definitive registration statement, as they become available, because they contain, or will contain, important information. Investors and security holders may obtain a free copy of the definitive joint proxy statement/prospectus (when it becomes available) and other documents filed by Lyondell and Millennium with the SEC at the SEC’s web site at www.sec.gov. The definitive joint proxy statement/prospectus (when it becomes available) and the other documents filed by Lyondell may also be obtained free from Lyondell by calling Lyondell’s Investor Relations department at (713) 309-4590.

The respective executive officers and directors of Lyondell and Millennium and other persons may be deemed to be participants in the solicitation of proxies in respect of the proposed transaction. Information regarding Lyondell’s executive officers and directors is available in the proxy statement filed with the SEC by Lyondell on March 16, 2004 and in the Form S-4, and information regarding Millennium’s directors and its executive officers is available in Millennium’s Annual Report on Form 10-K/A for the year ended December 31, 2003, which was filed with the SEC on April 27, 2004, and in the Form S-4. Other information regarding the participants in the proxy solicitation and a description of their direct and indirect interests, by security holdings or otherwise, will be contained in the definitive joint proxy statement/prospectus and other relevant materials filed with the SEC, as they become available.