The electrochemical mechanisms of chalcopyrite dissolution in the absence and presence of Sulfolobus metallicus at 70 degrees C were studied using cyclic voltammetry and Tafel methods. The cyclic voltammetry experiments show that S. metallicus does not change the oxidative and reductive mechanisms of chalcopyrite dissolution. The initial oxidation potentials of chalcopyrite dissolution are equal in the absence and presence of S. metallicus. However, the current density of oxidation in the presence of S. metallicus increases significantly. At about 0V. the products on the surface of chalcopyrite are CuS, elemental S(0), and Fe(2+). At about 0.384 V. CuS may be oxidized, and chalcopyrite may be transferred to CuO, Fe(2)O(3), and elemental S(0). The Tafel experiments show that S. metallicus may increase the corrosion potential and corrosion current density of chalcopyrite. S. metallicus may also reduce the polarization resistance of chalcopyrite in bioleaching. These results indicate that S. metallicus may accelerate the oxidation of chalcopyrite. (C) 2011 Elsevier Ltd. All rights reserved.