NOVELTY - The catalytic converter unit comprises a reformer catalytic converter (11) for treatment of a fuel for fuel cell and an oxidation catalytic converter for after treatment of an exhaust gas from the fuel cell. The oxidation catalytic converter is arranged annularly around the cylindrical reformer catalytic converter. Gas paths of the oxidation and reformer catalytic converters are separated by a metal pipe (13) that accommodates the reformer catalytic converter. The metal pipe has a sleeve (14) that forms a gas distribution housing for the reformer catalytic converter.    USE - The catalytic converter unit is useful for a high-temperature fuel cell system (claimed), and in a compact auxiliary power unit used to where to provide electrical and thermal energy to a motor vehicle.    ADVANTAGE - The catalytic converter unit has improved thermal conductivity, compact size, and low pressure loss.    DETAILED DESCRIPTION - The catalytic converter unit comprises a reformer catalytic converter (11) for treatment of a fuel for fuel cell and an oxidation catalytic converter for after treatment of an exhaust gas from the fuel cell. The oxidation catalytic converter is arranged annularly around the cylindrical reformer catalytic converter. Gas paths of the oxidation and reformer catalytic converters are separated by a metal pipe (13) that accommodates the reformer catalytic converter. The metal pipe has a sleeve (14) that forms a gas distribution housing for the reformer catalytic converter, and an inner pipe, which forms an inner wall of the annular oxidation catalytic converter. The reformer catalytic converter is inserted into the oxidation catalytic converter. The reformer catalytic converter and/or the oxidation catalytic converter comprises metallic, catalyst supports. The sleeve is present thermally conductive contact with the catalyst support of the reformer catalytic converter. The inner pipe is present thermally conductive contact with the catalyst support of the oxidation catalytic converter. The catalyst supports are firmly connected to adjacent parts of the pipe by a welding, soldering or sticking method, and include metallic, braided fabric, wire mesh or metallic, slat structure. The sleeve is inserted into the inner pipe at a distance of 0.2-1.5 mm using a loose fit. The sleeve and/or the inner pipe comprises a sealing flange. An annular seal such as a swellable mat is provided between the sealing flange and an end of the inner pipe. The sleeve is formed with engaging members or engagement holes on a trigger tool. The oxidation catalytic converter has a tubular outer wall having gas discharge ports projecting into an area through the catalyst support. The gas distribution housing is provided inside of reformer catalytic converter. A supply line for fuel-gas mixture is radially or tangentially provided with respect to an axis of the reformer catalytic converter, and opens into the gas distribution housing. The gas distribution housing includes an annular space in which the supply line for the fuel-gas mixture opens, and radial access openings arranged on surface of the reformer catalytic converter.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic three-dimensional, partial cut-away view of a catalytic converter unit.    Reformer catalytic converter (11)    Oxidation catalytic converter (12)    Metal pipe (13)    Sleeve (14)    Outer tube. (15)