Functional role of pre-fermentation of food waste (PFW) was studied to enhance the performance of single chambered microbial fuel cell (MFC) (mediatorless; non-catalyzed graphite electrodes; open-air cathode). Significant improvement in power output was noticed after pre-treatment (391 mV; 530 mA/m(2)) compared to unfermented waste (275 mV; 361 mA/m(2)). MFC performance was found to depend on applied organic load and nature of substrate in terms of power generation and substrate degradation. The pre-fermentation of waste facilitated lowering of activation losses and in turn increased the bio-electrochemical activity of biocatalyst, leading to an effective MFC performance. Fuel cell behavior with respect to polarization, anode potential and bio-electrochemical behavior also supported the performance of MFC with PFW. PFW operation showed higher catalytic current in voltammograms with fine catalytic peaks supporting the positive role of pre-fermentation in discharging electrons effectively. VFA and pH profiles also correlated well with power generation and substrate degradation pattern. Copyright (C) 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.