This study evaluates bioleaching treatments of chalcopyrite concentrate and smelter dust using mesophilic and moderately thermophilic bacterial cultures. Effects of some variable parameters such as solids concentration, temperature (type of bacteria) and inoculation on the bioleaching of the materials obtained from Sarcheshmeh copper complex were investigated. Bioleaching experiments were carried out in shaking incubator using mixed mesophilic and moderately thermoacidophilic bacteria. The results indicate that the efficiency of copper extraction is dependent on all the variables studied for both microorganisms. Maximum copper recovery from concentrate and dust was achieved using a moderately thermophilic culture. Under optimum conditions, copper dissolution from concentrate reached 87.52% with moderately thermophilic, and 34.55% with mesophilic culture, after 25 days. Also, overall copper extraction calculated for dust bioleaching were 92.00% with moderately thermophilic bacteria and 73.27% with mesophilic bacteria. (C) 2011 Elsevier B.V. All rights reserved.