NOVELTY - The reformer (3) for generating hydrogen gas-containing reformate gas from a hydrogen-containing fuel and an oxidator for fuel cell system, comprises a reformate gas line (14) connected at an outlet side (13) of the reformer for guiding away the reformate gas from the reformer, a line for recirculating the reformate gas to the reformer, and a recirculation heat exchanger (34), which is bound in the recirculation line and in oxidator line transporting a medium heatable with the recirculated reformate gas. A conveyor and a valve arrangement are arranged in the recirculation heat exchanger.    USE - Reformer for generating hydrogen gas-containing reformate gas from a hydrogen-containing fuel and an oxidator useful for fuel cell system for automobiles.    ADVANTAGE - The reformer ensures efficient production of reformate gas with reduced energy consumption and pollutant emission by increasing current availability.    DETAILED DESCRIPTION - The reformer (3) for generating hydrogen gas-containing reformate gas from a hydrogen-containing fuel and an oxidator for fuel cell system, comprises a reformate gas line (14) connected at an outlet side (13) of the reformer for guiding away the reformate gas from the reformer, a line for recirculating the reformate gas to the reformer, and a recirculation heat exchanger (34), which is bound in the recirculation line and in oxidator line transporting a medium heatable with the recirculated reformate gas. The recirculation line is connected to the reformate gas line on the one hand and to inlet side (15) of the reformer on the other hand. The oxidator line guides the oxidative gas to the reformer and/or the fuel cell (2). A conveyor and a valve arrangement are arranged in the recirculation heat exchanger. The valve arrangement connects a section of the recirculation line guiding by the valve arrangement for the reformer optionally with a section of the recirculation line guiding by the reformate gas line for the valve arrangement or with a further section of the recirculation line over which anode waste gas is guidable to the fuel cell of the reformer. A pre-reaction chamber is intended, on which the recirculation line and an oxidator line guiding the oxidator to the reformer are connected and which communicates the reformer with a mixture forming section on which a fuel line is connected to the reformer. A control is arranged that cooperates with components of the reformer or the fuel cell system and is arranged so that it is cooperated to the reformer or the fuel cell system for carrying out the process. INDEPENDENT CLAIMS are included for:    (1) a method for operating a reformer for generating hydrogen gas-containing reformate gas from hydrogen-containing fuel and oxidator;    (2) a method for operating a fuel cell system; and    (3) a fuel cell system for automobiles.    DESCRIPTION OF DRAWING(S) - The figure shows a principle representation of a fuel cells system.    Fuel cell (2)    Reformer (3)    Outlet side (13)    Reformate gas line (14)    Inlet side (15)    Recirculation heat exchanger. (34)