Anodic dissolution of chalcopyrite was studied using an electrochemical technique that allows direct measurements of the anodic dissolution current with small chalcopyrite particles. Experiments were conducted with a working electrode made of a single layer of chalcopyrite particles pressed onto adhesive conductive carbon tape. Potentiostatic anodic dissolution experiments of 8 h duration were conducted in deoxygenated iron-free sulfuric acid solutions at pH 1.7 and 70 degrees C, at potential values of 0.55, 0.6, 0.7, 0.8 and 0.9 V/SHE. Results showed that anodic dissolution of chalcopyrite involves two main reactions. First, chalcopyrite is anodically dissolved while reacting with protons through a 2 electron reaction which results in the formation of intermediate polysulphide compounds and dissolution of copper and iron. Secondly, the polysulphide intermediate layer is further oxidized to elemental sulfur or sulfate, which involves a much larger number of electrons. The kinetics of both reactions are interdependent and controlled by the applied potential.