To obtain high-purity copper sulfate with nickel content being a specific level or lower by such a practice that an aqueous solution of crude copper sulfate containing nickel as an impurity is heated to a specified temperature or higher, and copper sulfate separated and sedimented is then collected and subsequently dissolved in water again, and the resultant aqueous solution is concentrated to effect recrystallization of the objective copper sulfate.

This high-purity copper sulfate is obtained by the following procedure: an aqueous solution of nickel-contg. copper sulfate is heated to ≥80°C, and copper sulfate separated and sedimented is then collected and subsequently dissolved in water again, and the resultant aqueous solution is concentrated to effect recrystallization, thus obtaining the objective copper sulfate ≤0.001 wt.% in nickel content; for example, the procedure is as follows: pure water is added to 1.3 kg of copper sulfate to prepare a 2L aqueous solution, which is heated under vigorous agitation; after complete dissolution of the copper sulfate, the aqueous solution is kept at ≥85°C for 4 h, thereby concentrated to 0.8 L, the resultant yellow-green precipitate is filtered and separated; the precipitate is then dissolved in water again and subsequently recrystallized, thus affording the objective high-purity copper sulfate 0.0004 wt.% in nickel content in a single step concentration; wherein the pH of the aqueous copper sulfate solution prior to heating is pref. 1.7-4.5 and the upper limit of heating temperature is the boiling point 100-110°C at the atmospheric pressure.