A fuel cell assembly in which at least one heat exchanger for conditioning either the anode or cathode reactant gas is integrated with the fuel cell stack and located at the end of the fuel cell stack, to isolate the fuel cell stack from contact with the end plates of the stack. The heat exchanger may preferably be comprised of a stack of plates which may preferably be the same as the plates as the fuel cell stack, with outer and inner end plates to direct the flow of reactant gases, waste gases and coolant to and from the fuel cell stack. The assembly is preferably configured to include reactant conditioning heat exchangers at both ends of the fuel cell stack.