A method of operating a fuel cell

A fuel cell 2 which is operated at a temperature which is not greater than substantially 250 DEG C electrolyte, or a liquid alkaline electrolyte, and a cathode 4 and an anode 6 each comprising a platinum catalyst. Hydrogen fuel gas is supplied along conduit 10 to the anode 6 and a gaseous oxidant, for example oxygen is supplied along conduit 12 to the cathode 4. Electrical leads 14 and 16 from the cathode and anode are connected to circuits including a load 18 to be powered by the fuel cell 2, a battery 20 and switches S1 and S2 operated by control 22. When switch S1 is closed the cell 2 powers the load 18, and switch S2 is open. When switch S1 is open switch S2 is closed so the battery 20 applies a reverse D.C. potential the anode 6 and cathode 4. Switch S1 is closed and switch S2 is open for a time period T1 which is substantially at least ten times greater than time period T2 for which switch S1 is open and switch S2 is closed. The time period T2 does not exceed substantially 0.25 seconds. The switches can be relays or solid state electronic switch arrangements.