The ion exchange chromatography technique was used for studying copper isotope effects in Cu-malate ligand exchange system (LXS) in the temperature range 288-353K. A highly acidic cation exchange resin (TITECH-3, 37-88 mum) was used. It had been found that the heavier isotope, Cu-65, was enriched at the front boundary, while the lighter isotope, Cu-63, was enriched at the rear boundary of the copper band at all temperatures. Such finding means that the heavier isotope, Cu-65, is preferentially fractionated into the malic complex form in the solution phase. The values of the single stage separation coefficients, epsilon = S - 1, of the Cu-63/Cu-65 isotopic pair have been calculated and found to decrease with the increase in temperature as 2.87 x 10(-4), 2.39 x 10(-4), and 2.13 x 10(-4) at 288, 333, and 353K, respectively. The height equivalent to the theoretical plate (HETP), at every temperature, was also calculated.