Abstract: A method of leaching copper from copper sulphide-containing concentrates, such as chalcopyrite, includes using pyrite as a catalyst for ferric reduction in order to eliminate passivation of the chalcopyrite surface, the process being carried out under conditions whereby the pyrite is not materially oxidized, for example by maintaining the operating solution potential at a suitable level. The leaching is carried out in an acidic sulphate medium and may include oxidation by oxygen-containing gas. The leached copper is then recovered, for example by solvent extraction and electrowinning. The leaching process can result in the virtually complete extraction of copper at atmospheric pressure in as little as four hours.