Polyaniline (Pani), vanadium oxide (V2O5), and Pani/V2O5 nanocomposite were fabricated and applied as a cathode catalyst in Microbial Fuel Cell (MFC) as an alternative to Pt (Platinum), which is a commonly used expensive cathode catalyst. The cathode catalysts were characterized using Cyclic Voltammetry and Linear Sweep Voltammetry to determine their oxygen reduction activity; furthermore, their structures were observed by X-ray Diffraction, X-ray Photoelectron Spectroscopy, Brunauer-Emmett-Teller, and Field-Emission Scanning Electron Microscopy. The results showed that Pani/V2O5 produced a power density of 79.26 mW/m(2), which is higher than V2O5 by 65.31 mW/m(2) and Pani by 42.4 mW/m(2). Furthermore, the Coulombic Efficiency of the system using Pani/V2O5 (16%) was higher than V2O5 and Pani by 9.2 and 5.5%, respectively. Pani-V2O5 also produced approximately 10% more power than Pt, the best and most common cathode catalyst. It declares that Pani-V2O5 can be a suitable alternative for application in a MFC system. Copyright (c) 2013 John Wiley & Sons, Ltd.