A fuel cell system is for a vehicle at least partially propelled by an electric traction motor. The fuel cell system includes a fuel cell comprising an anode side and a cathode side, an expander connected to a fuel cell motor, an inlet conduit connected to an inlet end of the cathode side for supply of air to the cathode side, an outlet conduit connected between an outlet end of the cathode side and an inlet side of the expander for supply of an exhaust flow from the cathode side to the expander, and an exhaust conduit connected to an exhaust side of the expander, and a heat exchanger connected at the inlet conduit and at the exhaust conduit for transfer of heat between the inlet conduit and the exhaust conduit.