The Chitosan/Montmorillonite (CHI/MMT) nanocomposites (1/1, 1/2, 1/4 %w/w) are self-assembled over the ceramic separator of the microbial fuel cells (MFCs). The oxygen diffusion coefficient of the ceramic membrane has diminished about a hundred times which resulted in the better growth of exoelectrogenic anodic bacteria, boosting the electrical double layer capacitance by four orders of magnitude, and decreasing the charge transfer impedances of the anode and cathode electrodes by 96.44% and 66.14%. The ohmic resistance is dropped by 73.2%, owing to the improved proton conductivity of the modified ceramic membranes. The coulombic efficiency of 86.97 +/- 13.2% along with the power and current densities of 229.12 +/- 18.5 mW/m(2) and 1422.22 +/- 41.2 mA/m(2) are obtained during the start-up operation of the modified MFC by 1/2 (% w/w) CHI/MMT, which are more than three times higher than the values of the blank-ceramic. The wastewater treatment efficiency of the MFCs does not alter seriously. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.