NOVELTY - System for desulfurizing undiluted hydrocarbon fuel stream to convert it into a hydrogen-rich gas for use in a cell stack assembly in a fuel cell plant comprises: (a) nickel desulfurization station for converting sulfur in fuel stream to nickel sulfide; (b) means for introducing the undiluted fuel stream into the station; and (c) means for maintaining the station at 250-525 degrees F during operation.    USE - For desulfurizing an undiluted hydrocarbon fuel stream to convert it into a hydrogen-rich gas for use in a cell stack assembly in a fuel cell power plant.    ADVANTAGE - The system does not require the addition of steam or a hydrogen source to the fuel stream prior to desulfurizing. It operates at low temperatures and can be used to desulfurize either a liquid or gaseous fuel stream. The system can be used as a sole source of electricity for a vehicle or a stationary power plant, or could be used in a hybrid system which include batteries for electrical power or generators in addition to fuel cell electrical power source.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for:    (A) a method for desulfurizing an undiluted hydrocarbon fuel stream to convert it into a hydrogen-rich gas for use in a cell stack assembly in fuel cell power plant, comprising:    (a) providing an undiluted hydrocarbon fuel stream;    (b) providing a nickel desulfurization station with nickel reactant to convert sulfur in organic sulfur compounds in fuel stream to nickel sulfide;    (c) introducing hydrocarbon fuel stream into nickel station; and    (d) maintaining the station at 250-525 degrees F during operation; and    (B) a mobile wheeled land vehicle assemblage comprising:    (i) onboard electric motor for providing partial motive power;    (ii) onboard fuel cell stack assembly for providing electricity for the motor; and    (iii) onboard fuel processing system for desulfurizing an undiluted hydrocarbon fuel stream.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic view of a fuel processing system.    Fuel processing system (2)    Desulfurizer (8)    Boiler (14)    Autothermal reformer (20)    Heat exchanger (24)    Shift converter (30)    Oxidizer (50)    Ammonia scrubber (52)    Fuel cell stack assembly (55)