Fuel cell system

The fuel cell system (1) has a heat exchanger (11) for pre-heating a fuel/water mixture and an evaporation unit (9) for obtaining a gas flow from the pre-heated fuel/water mixture, fed through a cooled gas cleaning unit (3), for selective removal of carbon monoxide, before feeding the cleaned gas flow to the anode space (6) of at least one fuel cell (4). The gas cleaning unit is provided with a separate cooling unit (14), the heat exchanger connected downstream of the fuel cell cooling space (7), for removing heat from the fuel cell coolant flow.