A method for starting a gas generating system serving to generate a hydrogenous gas used for operating a fuel cell. The gas generating system includes: devices for converting starting materials into the hydrogenous gas; devices for conditioning at least a portion of the starting materials; devices for purifying the hydrogenous gas by removing unwanted gas constituents, and; a starting burner. According to the method, in a first method step, at least one fuel is combusted inside the starting burner. The hot waste gases resulting from this combustion firstly heat the devices provided for conditioning at least a portion of the starting materials, and the residual heat of these waste gases subsequently heats at least one additional component. In parallel thereto, the devices for converting the starting materials are heated by an electric heating. In a second method step, the starting materials are subsequently fed into the respective components of the aforementioned devices after a starting temperature has been reached. In a third method step, the quantitative proportions of the starting materials are then continuously modified in the direction towards the quantitative proportions provided for the normal operation of the gas generating system.