BACKGROUND: Microbial electrolysis cell (MEC) has been considered as a promising new technology for the production of bio-hydrogen from renewable biomass, but low-cost alternatives to typical cathode material (platinum) are needed. In this study, CNTs-based electrode alternatives to Pt were examined in a single-chamber membrane-free MEC. To the best of our knowledge, the use of carbon nanotube as the MEC cathode catalyst has not been reported so far. RESULTS: For all cathodes, hydrogen production rates increased in response to increase in voltage and the highest hydrogen production was achieved at 0.9 V. At an applied voltage of 0.9 V, MECs with Pt/MWNT cathodes obtained a hydrogen production rate of 1.42 m3 m-3 day-1 with a current density of 192 A m-3, a coulombic efficiency of 94%, a cathodic hydrogen recovery of 65%, and electrical energy efficiency based on electricity input of 126%. CONCLUSIONS: The Pt/MWNT cathode developed demonstrated better electrocatalytic activity than the MWNT cathode and achieved performance comparable with the Pt cathode in terms of hydrogen production rate. These results demonstrate the great potential of using carbon cloth with CNTs-based electrodes as a cathode material for MECs. Copyright (C) 2012 Society of Chemical Industry