In the present work, Water Hyacinth Biochar (WHB) was produced by pyrolysis at 900 degrees C and then characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), EDX-SEM, Fourier transform infrared (FTIR) spectroscopy, Brunauer-Emmett-Teller (BET) surface area and particle size analyses. The results indicate that WHB has Oxygen Reduction Reaction (ORR) catalytic activity, with an average of 2.58 electrons per oxygen molecule transferred from WHB for ORR. The ORR catalytic activity of WHB is attributed to its physical and chemical surface properties. The maximum power density produced from an air cathode single chamber microbial fuel cell (ACSC-MFC) with WHB as the ORR catalyst versus the Pt/C catalyst were 24.7 and 12.3 mWm(-2), respectively. This study demonstrates that Water Hyacinth Biochar can be used as an inexpensive catalyst for the ORR in microbial fuel cells. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.