NOVELTY - Fuel is dosed into the flow of oxidative gas and waste gases from the fuel cell (3) and/or from the gas production system (2) ahead of catalytic combustion.    USE - To vaporize and/or superheat a fuel, especially methanol/water mixture, to supply a catalytic oxidative reactor releasing the heat required when feeding a fuel cell reformer. The equipment forms e.g. part of a fuel cell power plant for an electric vehicle.    ADVANTAGE - A rapid dynamic response is achievable. Catalytic combustion is a particularly responsive method of realizing a large turndown ratio in a short interval. The system delivers increased power very rapidly, in reaction to demand. Oxidant addition takes place before catalytic combustion, requiring no further energy for fine distribution and/or for evaporation of the additional fuel used. Atomization to fine particles is all that is required to assure catalytic combustion. No separate source of heating or separate energy source (other fuel, electricity) is required.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for equipment carrying out the operation. In a first heat exchanger region (1a), fuel or fuel/water mixture is evaporated and/or superheated. In a second heat exchanger region (1b), there is a catalyst (4) promoting combustion (i.e. providing the required heat). A line (5) supplies waste gases from the fuel cell (3) and/or the gas production system (2) (i.e. a fuel cell reformer), for catalytic combustion. Ahead of the heat exchanger (1) there is a constriction (9) in the line, where the fuel is fed from a branch (6). In the main line ahead of the constriction, there is a connection (7) for oxidant supply.    Preferred Features: The fuel introduced, is atomized by a gas in a two-component nozzle. Fuel dosing and oxidative gas quantity are controlled in accordance with the required energy release for vaporization. In the apparatus, a valve (10) controls or regulates the fuel volumetric flow at the branch (6). The constriction is a venturi. The branch line section resembles a lance projecting close to the constriction. The connection (7) has a throttle valve (11). The connection discharges into the line (5) at a further constriction (9').    DESCRIPTION OF DRAWING(S) - The figure shows a schematic block diagram of the system.    Heat exchanger (1)    First heat exchanger region (1a)    Second heat exchanger region (1b)    Gas production system (reformer) (2)    Fuel cell (3)    Catalyst (4)    Main line (5)    Branch (6)    Connection (7)    Constriction (9)    Further constriction (9')    Valve (10)    Throttle valve (11)