Microbial fuel cells (MFCs) are the most useful technologies for energy production and wastewater treatment due to their low cost and support of the environment. In this study, the membrane fouling and their effects on power generation were investigated using scanning electron microscope (SEM). Results demonstrate that proton exchange membrane (PEM) was affected by biofouling in a two-chamber H-type MFC, which would significantly affect coulombic efficiencies (CEs), and maximum power densities leading to reduced power generation. The power densities of both rice straw and potato peels were 119.35 mW/m(2) and 152.55 mW/m(2), respectively. Scanning Electron Microscope (SEM) showed substantial accumulation of bacteria and their end-products forming a thick biofilm on the surface of PEM leading to a decrease, if not, preventing the passage of protons from the anode side toward the cathode side. The decline in power generation may result mainly from the biofouling, not of electrodes but, of PEM membrane from both sides (Anode and Cathode) because of improper regular PEM cleaning. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights