HOUSTON - Lyondell Chemical Co. announced an agreement to acquire Millennium Chemicals Inc. in a stock transaction valued at about $1 billion. The deal, if completed, would create the third largest publicly traded chemical manufacturer in North America. Lyondell also will assume $1.3 billion in Millennium debt, the companies said.

The merger will combine two important U.S. chemical companies that hold major positions in various commodities and specialty products, including titanium dioxide (TiO2), propylene oxide and acetyls. The companies also are partners in the Equistar joint-venture business, a producer of ethylene, propylene, polyethylene and aromatics. The two companies had combined 2003 revenues of more than $11 billion, and following the merger will operate in 16 countries and employ about 10,000 people worldwide.

Millennium, based in Hunt Valley, MD, is the second-largest producer of TiO2 in the world, and operates production facilities on four continents. The company also is a major supplier of acetic acid and vinyl acetate monomer, silica gel, cadmium-based pigments, acetic acid and vinyl acetate monomer.

The transaction, subject to approval by both companies' shareholders, is expected to close in the third quarter. The company will retain the Lyondell Chemical name and will be based in Houston. Lyondell's president and chief executive officer, Dan F. Smith, will hold those positions with the merged company.

Lyondell, headquartered in Houston, is a major producer of propylene oxide; propylene oxide derivatives including propylene glycol, butanediol and propylene glycol ethers; and styrene monomer and MTBE.