Anion-exchange chromatography of copper has been carried out to study copper isotope separation based on the Cu(I)/Cu(II) electron-exchange reaction at various temperatures. At every temperature the lighter isotope, Cu-63, was observed to be enriched at the rear part of the copper adsorption band. The results indicate that the lighter isotope is preferentially fractionated into Cu(I) ions in the resin phase. Single-stage separation coefficients, epsilon (= alpha - 1), were calculated for the Cu-63/Cu-65 isotopic pair at different temperatures. The results show that the separation coefficient epsilon obtained is decreased by increasing the temperature. The height equivalent of a theoretical plate (HETP) was determined in every experiment and found to be almost constant at different temperatures.