Washington officials and lawmakers will get a firsthand glimpse at the possibilities of hydrogen-power vehicles when General Motors Corp. and Royal Dutch/Shell Group bring half a dozen prototype models to the capital this spring and begin offering test rides. At some point, members of the public will be able to come along.

Although hydrogen-powered test vehicles are on the road elsewhere, the Washington area will have the nation's first service station equipped with a hydrogen pump, said Don Huberts, chief executive of Shell Hydrogen. Huberts did not say which Shell station will be get the pump.

The partnership symbolizes the need to perfect the technology of hydrogen cars and create a nationwide network of refueling stations, said Lawrence D. Burns, vice president for research and development at GM.

GM plans to have its first production-model hydrogen cars available by 2010. The new cars will run on electricity generated by onboard power cells fueled by hydrogen.

Huberts said Shell's hydrogen fuel will be produced initially from natural gas. The hydrogen cars will discharge half as much greenhouse-gas emissions as today's gasoline engines because of the fuel cell's improved efficiency. A zero-polluting vehicle requires hydrogen made from renewable fuels. A major shift in that direction will take several decades, he said.