NOVELTY - The reformer (3) for generating combustion gases containing hydrogen from a fuel containing hydrogen and an oxidizer containing oxygen for a fuel cell system (1) in a motor vehicle, comprises a mixture-producing zone (12) having a mixing chamber (14), in which a mixture is formed from the fuel and the oxidizer, and a conversion zone (13) having a catalyst (15), which converts the mixture into combustion gas by partial oxidation. An entrance end of the catalyst and an exit end of the mixing chamber directly adjoin or coincide. The mixture-producing zone has an evaporation zone.    USE - Reformer for generating combustion gases containing hydrogen from a fuel containing hydrogen and an oxidizer containing oxygen for a fuel cell system in a motor vehicle.    ADVANTAGE - The reformer can be manufactured with enhanced evaporation, less fuel consumption and high efficiency and is capable of directly allowing the thermal radiation from the catalyst into the mixing chamber or the evaporation zone thus improving the efficiency of the fuel cell system.    DETAILED DESCRIPTION - The reformer (3) for generating combustion gases containing hydrogen from a fuel containing hydrogen and an oxidizer containing oxygen for a fuel cell system (1) in a motor vehicle, comprises a mixture-producing zone (12) having a mixing chamber (14), in which a mixture is formed from the fuel and the oxidizer, and a conversion zone (13) having a catalyst (15), which converts the mixture into combustion gas by partial oxidation. An entrance end of the catalyst and an exit end of the mixing chamber directly adjoin or coincide. The mixture-producing zone has an evaporation zone, in which liquid fuel supplied during the operation of the reformer evaporates, at an entrance end of the mixing chamber. The mixture-producing zone and the conversion zone are arranged and aligned on each other. The evaporation zone has a porous evaporation body, in which the supplied liquid fuel distributes itself on a large surface. The heat from the catalyst directly radiates into the mixing chamber, evaporation zone or the evaporation body. An INDEPENDENT CLAIM is included for a fuel cell system in a motor vehicle.    DESCRIPTION OF DRAWING(S) - The figure shows a strongly simplified circuit diagram of a fuel cell system with a reformer.    Fuel cell system (1)    Reformer (3)    Mixture-producing zone (12)    Conversion zone (13)    Mixing chamber (14)    Catalyst. (15)