Abstract: A process for the production of substantially pure hydrated nickel sulphate which involves reacting sulphuric acid with nickel chloride at the boiling point of the reaction mixture and partially removing formed hydrogen chloride gas. The reaction mixture is clarified to separate impurities, the formed nickel sulphate is crystallized from the clarified mixture, and the mother-liquor obtained at this stage recycled to an earlier stage of the process. The crystals of nickel sulphate are dried and the mother-liquid obtained at this stage, then recycled to an earlier stage of the process. The hydrated nickel sulphate obtained is substantially pure and essentially free of chloride ions.