The Sulfidation-Leaching process for the treatment of chalcopyrite concentrates is a non SO2 polluting alternative for producing copper. This process consists of roasting chalcopyrite with sulfur at temperatures lower than 400 degrees C followed by leaching of the sulfidized material to dissolve the copper. The present work is concerned with the kinetic study of the pressure leaching of sulfidized chalcopyrite concentrate in H2SO4-O-2 solutions. The temperature range considered was 125-150 degrees C, and partial pressures of oxygen from 507 to 1216 kPa (5 to 12 arm). The results indicated that the copper dissolution rate increases with increasing temperature and partial pressure of oxygen. The leaching kinetics was analyzed by using a shrinking rim model given by: 1- (1- 0.45X) 1/3 = kt, which represented well the experimental data. The determined activation energy was 93.5 kJ/mol and the rate of copper dissolution was first order with respect to the partial pressure of oxygen. (C) 2007 Elsevier B.V. All rights reserved.