A method for changing a fuel cell system from a normal mode of operation over to a standby mode comprises the following steps: a) reducing the load withdrawal—via the electric circuit of the fuel cell stack—down to a load within the range from −1% to +5% around a load with an optimal system efficiency, b) regulating down the anode pressure down via the anode supply system, c) in the meantime, maintaining and controlling the cathode gas feed via the cathode supply system so that the pressure differential between the anode spaces and the cathode spaces does not exceed a prescribed maximum pressure differential, d) switching off the cathode gas feed if the pressure differential between the anode spaces and of the fuel cell stack and the environment has reached the prescribed maximum pressure differential, and e) switching off the load withdrawal via the external electric circuit at the latest when a prescribed minimum limit voltage of the fuel cell stack has been reached.