A fuel cell is disclosed which comprises a casing (12) and an electrode assembly in the casing. The electrode assembly comprises a porous substrate (36) and first and second electrodes (46, 48) on one side of the substrate. Third and fourth electrodes (60, 62) are provided on the other side of the substrate. Each electrode includes a tab (36, 38, 42, and 44) by means of which an electrical connection can be made to that electrode. There is electrolyte in the casing.