Nippon Mitsubishi Oil Corp., a leading Japanese oil distributor, and DaimlerChrysler Japan Holding, Ltd. announced Thursday that they have agreed to conduct joint research to promote vehicles powered by fuel cells.

Fuel-cell powered vehicles that use a motor driven by electricity generated through chemical reactions between hydrogen and oxygen are expected to replace gasoline and diesel engines in the future because they do not emit pollutants.

Emission-free cars are seen as the most promising vehicles for the future.

The two firms will research subjects such as the development of fuel cells and infrastructure for the cars toward the 21st century, they said.

The two companies plan to carry out a trial run of the vehicles in Japan by the end of next year and conduct road tests in the future.

Because liquid hydrogen is highly flammable and difficult to handle, automakers are trying to find ways to extract hydrogen from methanol and gasoline, making it necessary for them to work with oil companies with expertise in liquid fuel.

DaimlerChrysler Japan Holding is a subsidiary of DaimlerChrysler AG that formed a partnership with Ford Motor Co. and Ballard Power Systems of Canada to develop automotive fuel-cell technology.

DaimlerChrysler plans to launch the vehicles around 2004, they said. Nippon Mitsubishi, the product of the April merger of Nippon Oil Co. and Mitsubishi Oil Co., has expertise in fuel-cell research carried over from Mitsubishi Oil, which had engaged in joint research and development of fuel cells with Mitsubishi Motors Corp.