A microbial fuel cell (MFC) can use wastewater as a substrate; hence, it is essential to understand its performance when seeded with different inocula and during the treatment of carbohydrate-rich wastewaters to simultaneously optimize electricity production and wastewater treatment. This study investigates the performance of single-chamber membraneless MFCs used to treat three different carbohydrate-rich synthetic wastewaters (glucose, sucrose, and soluble starch) while seeding with two different inocula (a microbial solution containing different species of microorganisms, and anaerobic sludge). The results showed that the highest voltages, power densities, and COD removal effi ciencies were obtained using microbial fuel cells fed with glucose-based synthetic wastewater, and were 351 mV, 218 mW/m², and 98.8%, respectively, for the microbial solution, and 508 mV, 456.8 mW/m², and 94.3%, respectively, for the anaerobic sludge. The lowest results of voltages, power densities, and COD removal effi ciencies were obtained using microbial fuel cells fed with the soluble starch-based synthetic wastewater, and were 281 mV, 139.8 mW/m², and 86.4%, respectively, for the microbial solution, and 396 mV, 277.6 mW/m², and 79.4%, respectively, for the anaerobic sludge. In all experiments, the voltages and power densities obtained for the anaerobic sludge were higher than those obtained for the microbial solution, and the COD removal effi ciencies obtained for the anaerobic sludge were less than those obtained for the microbial solution. This study determined that voltage generation, power densities, and COD removal effi ciencies were inversely proportional to the complexity of the carbohydrate used in single-chamber microbial fuel cells.