NOVELTY - The operation of a fuel cell system (1) for an automobile, comprises a fuel cell (2) for the steam generation out of combustible gas and oxidizer gas, and a reformer (3) with a catalyst (15) for the generation of combustible gas from fuel and oxidizer gas, by which a regeneration process for the catalyst ends, as long as oxygen in the gas stream is determined downstream of the reformer. The regeneration process is started only then, if the temperature of the catalyst lies below a predetermined regeneration target temperature.    USE - For the production of electricity for automobiles.    ADVANTAGE - The method completely avoids the destroy of the catalyst and anode side of the fuel cell system caused by the temperature resulting from the burning of the particles or soot loadings, and interruption of the reforming process and fuel cells process caused by the reaction products resulting from the burning and the regeneration of the catalyst.    DETAILED DESCRIPTION - The operation of a fuel cell system (1) for an automobile, comprises a fuel cell (2) for the steam generation out of combustible gas and oxidizer gas, and a reformer (3) with a catalyst (15) for the generation of combustible gas from fuel and oxidizer gas, by which a regeneration process for the catalyst ends, as long as oxygen in the gas stream is determined downstream of the reformer. The regeneration process is started only then, if the temperature of the catalyst lies below a predetermined regeneration target temperature. A conversion process for the conversion of anode waste gas and combustible gas with oxygen available in the fuel cell process is carried out after the deactivation of the fuel cell process. The conversion process is an integral part of the regeneration process and/or carried out before the regeneration process and/or directly passes over into the regeneration process. The gas stream that is supplied into the catalyst is cooled in between the conversion process and the regeneration process and/or is cooled down before the conversion process and/or is cooled down either during the conversion process and/or during the regeneration process. The gas is cooled in such a manner that the gas stream is promoted in a closed cycle (51), which goes through the anode of the fuel cell through a heat exchanger (41) that withdraws the heat from the gas flow, through the reformer and further through the anode of the fuel cell. The heat exchanger supplies the heat that is withdrawn from the gas stream of the cycle, into the cathode of the fuel gas cells and/or in the cycle (51) relative to the environment of the fuel cell system a low-pressure prevails and/or a gas pressure storage is mounted to the cycle, so that volume differences of the gas stream within the cycle can be adjusted and/or the gas stream during the regeneration process and/or during the conversion process is promoted in the cycle and/or the need dependent oxidizer or gas for the cycle during the regeneration process and/or during the conversion process is supplied upstream of the catalyst and/or the need dependent oxidizer gas for the cycle during the regeneration process and/or during the conversion process is taken downstream of the catalyst. During the starting of the fuel cell process, gas is promoted in the cycle, so that the temperature of the reformer is raised at the start of the reformer process. An INDEPENDENT CLAIM is included for a fuel cell system for an automobile.    DESCRIPTION OF DRAWING(S) - The figure shows a fuel cell system for automobile.    Fuel cell system (1)    Fuel cell (2)    Reformer (3)    Catalyst (15)    Heat exchanger (41)    Cycle. (51)