Nitrogen (N) was doped in situ in the nickel (Ni) nanoparticle (NP)-dispersed carbon nanofibers (CNFs) that were grown on an activated carbon fiber (ACF) substrate, using catalytic chemical vapour deposition. Acetonitrile served as the single source of carbon and N for growing and doping CNFs, respectively. The prepared N-Ni-CNF/ACF was directly used as the electrodes in a microbial fuel cell (MFC) for bioelectricity production. The performance of MFCs considerably improved using the N-doped material, with the maximum power density measured to be 1850 +/- 20 mW/m(2), which was approximately two-fold higher than that of the Ni-CNF/ACF (without N-doping)-based MFCs. Furthermore, the charge transfer resistance of the N-Ni-CNF/ACF electrode -based MFC was significantly low. The N-doping provided a favourable growth condition for bacteria; enhanced the electrical conductivity of the electrode material, and improved the electro-catalytic activity towards oxygen reduction at the cathode. The method of N-doping the Ni-CNF/ACF electrode is simple and effective, and the prepared N-Ni-CNF/ACF is a promising electrode material for MFCs. (C) 2015 Elsevier Ltd. All rights reserved.