Improved water distribution can be obtained within the cells of a fuel cell series stack by maintaining a suitable temperature difference between the cathode and anode sides of each cell in the stack during shutdown. This can be accomplished by thermally insulating the ''hot'' end and sides of the stack and by providing a thermal mass adjacent to the ''hot'' end. The fuel cell stack may also comprise first and second end plates, the second end plate having a heat rejection surface; a thermal mass interposed between the first end plate and the end cell and in thermal communication with the endcell; a first insulating layer interposed between the first end plate and the thermal mass; and a second insulating layer surrounding the plurality of fuel cells.