In this study, single-chamber microbial fuel cells (MFCs) were inoculated with sedimentary samples taken from one freshwater shallow lake. After 98 days of operation, it was found that sedimentary inocula had strong effect on MFC performances, and Fe(III) contents in sediments were significantly related to voltage values produced from MFCs. Inoculation of the sedimentary sample from the site with the highest Fe(III) content led to the production of the highest voltage with a value of 580 mV, while voltage from the MFC inoculated with sediments from the site with the lowest Fe(III) concentration was less than 30 mV at the end of the experiments. In addition, microbial communities of anode biofilms from the MFCs with the highest and lowest voltages showed significant difference. This study will help enable scientific decisions to be made regarding the selection of freshwater sediments as MFC inoculum, and survey exoelectrogenic microorganisms within sediments. (c) 2011 Elsevier Ltd. All rights reserved.