NOVELTY - A hydrocarbon stream is desulfurized by providing a nickel reactant desulfurization station that converts sulfur contained in organic compounds of the fuel stream to nickel sulfide. A hydrocarbon fuel stream containing molecular hydrogen additive is introduced into the nickel reactant desulfurization station.    USE - The method is for the desulfurization of hydrocarbon fuel stream, e.g., gasoline or diesel fuel stream, to convert the hydrocarbon fuel stream into a low sulfur content fuel. The low sulfur content fuel can be used to power a fuel cell power plant in a mobile environment, e.g., automobile, bus, truck or boat, or in a stationary environment.    ADVANTAGE - The method effectively removes organic sulfur compounds found in gasoline or diesel to levels that will not poison the catalysts in the fuel processing section of the fuel cell power plant assembly. It utilizes H2 additive that prevents or minimizes carbon formation in the nickel reactant desulfurization station, thus extending the useful life of the reactant desulfurization station.    DETAILED DESCRIPTION - Desulfurization of hydrocarbon stream involves providing a nickel reactant desulfurization station (8) that converts sulfur contained in organic compounds of the fuel stream to nickel sulfide. A hydrocarbon fuel stream containing molecular hydrogen additive is introduced into the nickel reactant desulfurization station. The H2 additive is present in an effective amount to provide an effluent fuel stream at an exit end of the nickel reactant station. The effluent fuel stream contains not more than 0.05 ppm sulfur.    An INDEPENDENT CLAIM is also included for a desulfurizing system comprising the nickel reactant desulfurization station that converts sulfur contained in organic compounds of the fuel stream to nickel sulfide, a mechanism for introducing hydrocarbon fuel stream into the nickel reactant desulfurization station, an H2 additive supply, and a hydrogen recycle line (30, 38) for connecting the H2 additive supply to the fuel stream.    DESCRIPTION OF DRAWING(S) - The figure is a schematic drawing of the desulfurizing system for gasoline or diesel fuel stream.    Nickel reactant desulfurization station (8)    Selective oxidizer (28)    Hydrogen recycle line (30, 38)