Activation of sulphide minerals by copper sulphate is common practice on platinum group mineral (PGM) concentrators. However, the role of copper sulphate in the flotation of PGMs is still unclear especially in the case of those PGM ores which contain relatively low concentrations of sulphides. This study was conducted to determine, using electrochemical techniques, the effect which the presence of copper sulphate has on the surface reactions occurring between xanthate collectors and minerals which are representative of those treated in PGM concentrators. Specifically rest potential and cyclic voltammetry measurements were conducted on the minerals moncheite (PtTe2) and cooperite (PtS) at pH 6, 8 and 10. The results were interpreted by relating them to previous reports using the same minerals which included micro-flotation and X-ray photoelectron spectroscopy (XPS) studies. Electrochemical interactions between cooperite and CuSO4 were observed to be occurring at all the pHs considered, whereas no significant interactions were seen in the case of moncheite. In the presence of SEX as a collector, CuSO4 was shown to inhibit the electrochemical interactions of xanthate with both the sulphide and telluride mineral surfaces and this is consistent with the observations reported previously on the negative effect of copper sulphate on the flotation of these minerals.