It has been proposed in the literature that the leachingLeaching of chalcopyrite in sulfateSulfate or chlorideChloride media can occur through a combined non-oxidative/oxidative mechanism, where H2S forms an intermediary species, and which is thought to occur concurrently with the oxidative leachingLeaching. Some studies have noted that elevated concentrations of Cu(II) improve chalcopyrite leachingLeaching in sulfateSulfate media. In this study, we investigate the role of Cu(II) in the so-called non-oxidative/oxidative process through electrochemical tests on a chalcopyrite electrode. The results are consistent with the formation of H2S through non-oxidative leachingLeaching of chalcopyrite. The H2S subsequently reacts with cupric ion to form intermediate cuprous sulfideSulfide species, which can be readily oxidized by dissolved oxygen. The findings support the feasibility of running heap leachingHeap leaching of chalcopyriteChalcopyrite-rich ores at elevated copperCopper concentrations in either chlorideChloride or sulfateSulfate systems.