This study investigates the influence of sequential batch feeding of different substrates such as ethanol, lactose, sucrose, starch, molasses, and methanol, which starts with acetate on power generation in a microbial fuel cell (MFC). After eleven sequential batches, enrichment with acetate and reaching the acceptable and stable amount of current, switching of the substrate was started. The complexity of the substrate influenced the MFC performance in terms of both the power production and the COD removal. The obtained results revealed that the average values of power density for acetate, ethanol, lactose, sucrose, starch, molasses and methanol, were 513, 376, 388, 349, 315, 328 and 10 mW m(-2), respectively. Lactose and sucrose fed MFC resulted in the same performance during the switching of lactose to sucrose because of the same complexity of these two substrates and capability of adapted biofilm in lactose-fed MFC for sucrose degradation. Furthermore, the kinetic constant for COD consumption and rate of electron generation were investigated. Based on COD analysis in the MFC fed with acetate, ethanol, and molasses, it is concluded that the COD consumption followed the first-order kinetics, and the calculated kinetic constant for all three MFCs was approximately the same, approximately equal to 1.45 d(-1).