This study reports that Fenton's reaction is capable of facilitating cathodic reaction and thus increasing the current output in microbial fuel cells (MFCs). The hydroxyl radicals ((OH)-O-center dot) produced via Fenton's reaction are demonstrated to be vital to the enhancement of electricity generation in MFCs. In a two-chamber MFC employing expanded polytetrafluoroethylene (e-PTFE) laminated cloth as a separator, the power output is enhanced approximately four times with Fenton's reaction. However, the enhancement lasts only a short time period due to the rapid consumption of Fenton's reagents. To overcome this problem, a Fe@Fe2O3/carbon felt (CF) composite cathode is made, which results in a greater and, more importantly, sustainable power output. In the composite cathode, Fe@Fe2O3 functions as a controllably releasing Fenton iron reagent and CF functions as an air-fed cathode to electro-generate H2O2. This newly developed MFC with a Fenton system can ensure a continuous high power output, and also provides a potential solution to the simultaneous electricity generation and degradation of recalcitrant contaminants. (C) 2009 Elsevier B.V. All rights reserved.