Abstract: Microbial fuel cells (MFCs) hold great promise as an alternative for direct biochemical energy extraction from both biomass and wastewater. However, the commercialization and scaling-up of MFCs is not completely feasible, due to the high price of platinum (Pt) as a cathode catalyst. In this paper, we studied the use of a carbon nanotube (CNT) composite catalyst, to reduce the amount of Pt (without decline of efficiency) for moving towards the commercialization of MFCs. CNT/Pt composite electrodes would increase MFC power output by 8.7–32.2%; with respect to the pristine Pt as a catalyst for the cathode at a chemical oxygen demand (COD) substrate of 100mg/l and 2000mg/l, respectively. Moreover, the amount of Pt in the CNT/Pt electrode could be reduced by up to 25% of the amount necessary for a conventional Pt/carbon electrode. [Copyright &y& Elsevier]