The present invention discloses a fuel cell system that comprises a fuel cell stack (10) comprising an anode flow field and a cathode flow field; a fuel supply line (12) for supplying a hydrogen-containing fuel to the anode flow field; a fuel inlet valve (18) in the fuel supply line upstream of the fuel cell stack; and an accumulator (32) comprising an upstream inlet (39) and a downstream outlet, the inlet fluidly connected to the fuel supply line and the outlet (36) fluidly connected to the fuel inlet valve.