Chalcopyrite is not only the most abundant but also one of the most refractory sources of copper. In this study, leaching experiments showed that leaching ef？ciency increases with increasing amounts of pyrite. In the absence of the addition of pyrite, chalcopyrite was leached at an approximate rate of 0.03 g/L/day. This rate increased to approximately 0.29 g/L/day when the pyrite/chalcopyrite (Py/Cp) weight ratio was 5. Polarization curves show that the icouple/icorr value was 1.71 at a cathode to anode (Sc/Sa) area ratio of 1:1. Galvanic corrosion tests of current con？rmed that the chalcopyrite leaching selectivity improved with an increasing Py/Cp ratio. Electrochemical impedance spectroscopy (EIS) results showed that the chalcopyrite electrochemical dissolution (leaching) rate depended on the charge transfer at the double layer and the passive ？lm characteristics and that the chalcopyrite corrosion rate decreased as soak tim