Fuel cell system and operating method

A fuel cell system comprises a fuel cell main body 31 containing a fuel cell 30 having an anode side 32 at which fuel is reacted, exhaust products arising at the anode side 32 of the fuel cell 30 as a result of the reaction at the anode side 32. A recirculation passage 40 is located inside the fuel cell main body 31 and recirculates a proportion of the exhaust products directly to the anode side 32 of the fuel cell 30 for reaction at the anode side 32. The recirculation passage 40 may include an ejector arrangement 46 for mixing fresh fuel with the recirculated exhaust products and may also include a reforming catalyst 47 for partially reforming the mixture in the recirculation passage 40.