Abstract: Process electrolyzes hot, concentrated solutions of (1) as an anolyte, an essentially saturated aqueous solution of an alkali metal chloride and (2) as a catholyte, an aqueous solution containing 10 to 75%/wt. of phosphoric acid separated by a special high-normality cation exchange membrane producing anodic chlorine of high purity, cathodic hydrogen also of high purity and in the catholyte an alkali metal phosphate. The process operates at temperatures of 75.degree. to 105.degree. at highest current efficiencies and with low power consumption. With a KCl anolyte, potassium phosphate salts of any desired K:P molar ratio are formed in the catholyte and which are useful in fertilizer and detergent applications. The process requires a cation exchange membrane of normality in the range of 0.2 to 10 N or higher in which a significant proportion of the anion sites may not be covalently-bound to the material of the membrane.