A fuel cell system has a water reservoir heater (40) of sufficient power for complete evaporation of the anti-freeze content of the water. A fuel cell system has a heater (40) which is used for heating a liquid (especially water) reservoir (30) in the fuel and/or oxidant supply line (23, 25) and which has a heating power sufficient for complete evaporation of anti-freeze contained in the liquid, the evaporated anti-freeze being collected and condensed for return to the reservoir (30).
