1,214,359. Fuel cell gas supply. ALLMANNA SVENSKA ELEKTRISKA A.B. 24 April, 1968 [25 April, 1967], No. 19288/68. Heading H1B. A fuel cell electrode forming at least part of a wall of a gas chamber through which an electrode active gas can pass from an inlet to an outlet is characterized by a porous wall situated across the chamber in the path of the gas, the wall covering no more than 25% of the electrode surface and effecting a gas pressure drop at least equal to half of the total gas pressure drop from inlet to outlet. The wall may be a sheet of fibres or sintered particles, situated midway between the inlet and outlet perpendicular to the direct flow of gas from one to the other. It may be made from a metal or thermoplastic, e.g. P.T.F.E. or poly(ethylene glycol terephthalate). If of metal, it may constitute an electrical connection. A fuel battery may comprise a plurality of such electrodes having a common inlet channel and a common outlet channel. The gas may be oxygen, air, ammonia or a mixture of nitrogen and hydrogen produced by cracking ammonia. In a particular embodiment (Figs. 1-3, not shown) a fuel cell battery comprises a stack of electrodes having circular frames which are thicker than the electrodes themselves so as to space them and provide alternate reactant and electrolyte chambers. The electrodes are of nickel activated with platinum and have a finer pored layer on the electrolyte side. The electrolyte is aq. KOH. The stack is held together by bolts, the joins between the frames being sealed by washers or by sticking them together. Eight bores for the supply and removal of fuel, oxident and electrolyte and for electrical connection pass through peripheral frames, all being open at the same end of the battery, the other end being closed by an end-plate which has no holes in it.