This paper investigates the effects of five flotation reagents (ethyl xanthate, isopropyl xanthate, butyl xanthate, isoamyl xanthate and butylaminel) on the bioleaching capability of Acidthiobacillus ferrooxidans. It is shown that these five flotation reagents can all depress the copper extraction of At.f(6) bacteria. According to the impacts from weak to strong, the inhibition effects of these five reagents on At.f(6) bacteria are in the following order: butyl xanthate, isopropyl xanthate, isoamyl xanthate, ethyl xanthate, and butylamine. The analysis of SEM-EDS indicates that the surfaces of mineral particles are corroded by different degrees and that the weight proportion and atomic number proportion of Cu decrease, but the weight proportion and atomic number proportion of Fe and S increase; the degrees of change are in the same order with the inhibition effects of these five reagents on bioleaching capability of At.f(6) bacteria. (c) 2012 Elsevier Ltd. All rights reserved.