Three types of aerobic bacteria such as Citrobacter freundii, Proteus mirabilis and Bacillus subtilis were evaluated in terms of bioelectricity production using double chambered microbial fuel cell (MFC) with graphite cloth as anode and cathode and Nafion membrane as proton exchange membrane (PEM). Performance of MFC was studied with addition of glucose. Cyclic voltammetry (CV) experiments showed the presence of peaks at -92 and -163 mV vs Ag/AgCl for C. freundii and P. mirabilis indicating their electrochemical activity without an external mediator. Potential time experiments showed the potential of MFC solely depend on change in anode potential rather than cathode potential. The internal resistance of MFC containing B. subtilis was lower than C. freundii and P. mirabilis. Fuel cell performance was evaluated employing polarization curve and power output along with cell potentials. MFC containing B. subtilis with neutral red mediator showed current output of 112 mA m(-2) at external resistance of 0.3 k Omega which is higher than the current outputs from MFC containing C. freundii and P. mirabilis. The relative efficiency of power generation observed in aerobic microenvironment may be attributed to the effective substrate oxidation and good biofilm growth observed on the anodic surface. Copyright (C) 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.