For the first time, the hollow-spherical Co/N-C nanoparticles doped in activated carbon was used in air-cathode microbial fuel cells (MFCs). Hereof, the Co/N-C nanoparticles, which combines the advantageous features of high surface area, sufficient active sites and high degree of graphitization, had been synthesized via a simple hydrothermal reaction followed by heat treatment. As a result, the Co/N-C showed superior catalytic activity, lower internal resistance, excellent kinetic activity towards oxygen reduction reaction (ORR) in MFCs. The maximum power density of MFCs with 10%Co/N-C air cathode was as high as 2514 ± 59 mW m², almost 174% higher than the control. Therefore, it can be expected that the as-synthesized Co/N-C, with extraordinary electro-catalytic performance towards ORR comparable to commercial Pt/C, will be a promising alternative to the state-of-the-art non-precious metal ORR electro-catalysts for electrochemical energy applications.