Non-platinum based cathodes were recently developed by electrodepositing NiMo on carbon cloth, which demonstrated good electrocatalytic activity for hydrogen evolution in microbial electrolysis cells (MECs). To further optimize the electrodeposition condition, the effects of electrolyte bath composition, applied current density, and duration of electrodeposition were systematically investigated in this study. The developed NiMo catalysts were characterized with scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) and evaluated using chronopotentiometry and in MECs. The optimal condition for electrodeposition of NiMo on carbon cloth was determined as: a Mo/Ni mass ratio of 0.65 in electrolyte bath, an applied current density of 50 mA/cm(2) and electrodeposition duration of 10 min. Under this condition, the NiMo catalyst has a formula of Ni(6)MoO(3) with a nodular morphology. The NiMo loading on the carbon cloth was reduced to 1.7 mg/cm(2) and the performance of MEC with the developed NiMo cathode was comparable to that with Pt cathode with a similar loading. This result indicates that a much lower cathode fabrication cost can be achieved compared to that using Pt catalyst, and thereby significantly enhancing the economic feasibility of the MEC technology. (C) 2010 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.