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. A method of shutting down a fuel cell stack having at least two fuel cells stacked in series, each fuel cell having a cathode side and an anode side, the method comprising: stopped the generation of electricity from the stack; allowing the stack to cool over a cooldown period; and maintaining a temperature difference between the cathode side and the anode side of each fuel cell during the cooldown period, wherein the direction of the temperature difference in each fuel cell is the same. The fuel cell stack may comprise coolant channels, Peltier devices and anode and cathode reactant flow fields.