The initial stages of the dissolution of chalcopyrite have been studied using rotating ring-disk electrode techniques in dilute sulfuric acid solutions at 60 degrees C. It has been confirmed that the mineral undergoes a dissolution process under freely dissolving conditions in the absence of an oxidant. This process involves the formation of soluble copper(II) ions and a soluble sulfur species which is presumably H2S. By the use of an anodic stripping technique on the ring electrode, it has been possible to determine that the dissolution of chalcopyrite under oxidative conditions involves a soluble sulfur species such as thiosulfate. Collection efficiency measurements involving the detection of both iron(II) and copper(II) on the ring have been used to identify possible anodic reactions in the potential region relevant to the oxidative leaching of the mineral.