The feasibility of recovering metal values and removing hazardous elements from the Pb/Zn smelting slag using bioleaching technique were studied through a flask experiment, and the community characteristics of the indigenous mode rate-thermophilic bacteria in this bioleaching system were also analyzed through a culture-independent restriction fragment length polymorphism (RFLP) of 16S rRNA genes approach. The results show that more than 80% of Al, As, Cu, Mn, Fe and Zn in the Pb/Zn smelting slag were leached at 65 degrees C, pH 1.5, pulp density 5%, but only about 5% of Pb. Phylogenetic analysis revealed that the bacteria in the bioleaching system mainly fell among Firmicutes. Gammaproteobacteria and Betaproteobacteria, and the dominant bacteria are affiliated with Bacillus spp., Sporosarcina spp. and Pseudomonas spp. (C) 2008 Elsevier Ltd. All rights reserved.