A novel polymer-metal nanoparticle-carbon micro-nanofiber-based nanocomposite was developed as an efficient air-cathode of a membrane-less single chamber microbial fuel cell (SMFC) for bio-energy production using Escherichia coli as a microbial catalyst. The polymeric material was synthesized using suspension polymerization, with polyvinyl alcohol as a monomer and poly methyl vinyl ether-alt-maleic anhydride (PMVEMA) as a cross-linking agent. The synthesized polymer composite was coated over the alumina (AA) and nickel (Ni) nanoparticles (NPs)-dispersed multi-scale web of activated carbon fiber (ACF) and carbon nanofiber (CNF). The PMVEMA polymer facilitated proton exchange from anolyte to cathode in SMFCs. AA:Ni-ACF/CNF served as an electron acceptor as well as the catalyst for atmospheric oxygen reduction at the cathode. The polarization curves determined using linear sweep voltammetry demonstrated the prepared polymer-metal-carbon nanocomposite to be an efficient air-cathode of the SMFC with a maximum electrical potential of 980 +/- 10 mV and a maximum power density of 1270 +/- 30 mW/m(2). Copyright (C) 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.