Two-chamber microbial fuel cells (MFCs) were operated to remove sulfide and nitrate simultaneously using activated sludge in this study. Compared with control experiment, the MFC showed its ability to remove nitrate and sulfide simultaneously and generate electricity. When the external resistance was 1000 0, the initial concentrations of sulfide and nitrate were about 60 and 10.5 mg L-1, respectively, maximum current density of the MFC was 138.31 mA m(-2). In the end of a typical cycle, it decreased to 12.20 mA m(-2). The main end products were nitrogen and sulfate. The microorganisms attached to the anode electrode had electrochemical activity, and the transfer mechanism of electron in MFC was different from that in control MFC. (C) 2012 Elsevier Ltd. All rights reserved.