Abstract: An electrode which comprises a substrate of a valve metal or an alloy thereof having properties similar to those of the valve metal and a coating comprising an outer layer which comprises RuO.sub.2, an oxide of at least one non-noble metal and at least one other noble metal or oxide thereof and an intermediate layer having a composition different from that of the outer layer and which comprises RuO.sub.2 and an oxide of at least one non-noble metal. The electrode is particularly useful as an anode for an electrolytic cell, eg a chlor-alkali cell, it has a lifetime therein which is greater than the sum of the operational life-times of electrodes which comprise a valve metal substrate and which separately comprise one of the above layers which together form a part of the coating of that electrode.

Abstract: A method of treating the surface of a cathode in order to remove therefrom deposited iron, the cathode comprising a metallic substrate at least part of the surface of which has been activated in order to reduce the hydrogen overvoltage at the cathode when the cathode is used in the electrolysis of water or aqueous solutions, and the method comprising contacting the surface with a liquid medium which reacts with and solubilizes the deposited iron.Removal of deposited iron results in a decrease in the hydrogen overvoltage of the cathode. The liquid medium may be an aqueous acidic solution and the cathode may be contacted with the liquid medium in situ in the electrolytic cell.

Abstract: A diaphragm of a porous sheet of an organic polymer for example, polytetrafluoroethylene, which contains a wetting agent distributed throughout the thickness of the sheet, the concentration of the wetting agent in that part of the sheet near to one or to both outer surfaces of the sheet being greater than the concentration of the wetting agent in that part of the sheet remote from the outer surfaces of the sheet.

Abstract: An electrode, for use in an electrolytic cell, which electrode is associated with a reference electrode adjacent to a surface of said electrode, in which the electrode comprises at least two spaced apart members, at least one of which is foraminate and which comprises an operative electrode surface, and in which the reference electrode is positioned between and spaced apart from said members.A reference electrode may be associated with an anode, and a reference electrode may be associated with a cathode, and the potentials associated with various cell parameters may be monitored, for example over potentials at the anodes and cathodes.

Abstract: A cathode for use in an electrolytic cell which comprises a metallic substrate, preferably of nickel alloy, and a coating thereon of a mixture of at least one platinum group metal and at least one platinum group metal oxide, the coating comprising from 2% to 30% by weight of platinum group metal. In the electrolysis of water or an aqueous solution e.g. an alkali metal chloride solution, the cathode has a low hydrogen over-voltage.

Abstract: A process for the production of a porous diaphragm suitable for use in an electrolytic cell, particularly a chlor-alkali cell, characterized in that the process comprises irradiating a porous shaped article of an organic polymeric material, for example, a sheet of a fluoropolymer, with high energy radiation, the irradiation being effected in the presence of, or the irradiated shaped article being subsequently contacted with, a reactant selected from ammonia, carbon monoxide and phosgene, and the sheet preferably being subsequently contacted with an aqueous alkaline solution.