Feasibility Of using chocolate industry wastewater as a substrate for electricity generation using activated sludge as a source of microorganisms was investigated in two-chambered microbial fuel cell. The maximum current generated with membrane and salt bridge MFCs was 3.02 and 2.3 A/m(2), respectively, at 100 Omega external resistance, whereas the maximum current generated in glucose powered MFC was 3.1 A/m(2). The use of chocolate industry wastewater in cathode chamber was promising with 4.1 mA current output, Significant reduction in COD, BOD, total solids and total dissolved solids of wastewater by 75%, 65%. 68%, 50%, respectively, indicated effective wastewater treatment in batch experiments. The 16S rDNA analysis of anode biofilm and suspended cells revealed predominance of beta-Proteobacteria clones with 50.6% followed by unclassified bacteria (9.9%), alpha-Proteobacteria (9.1%), other Proteobacteria (9%), Planctomycetes (5.8%), Firmicutes (4.9%), Nitrospora (3.3%), Spirochaetes (3.3%), Bacteroides (2.4%) and gamma-Proteobacteria (0.8%). Diverse bacterial groups represented as members of the anode chamber community. (C) 2009 Published by Elsevier Ltd.