Performance of cathode electron receivers has direct effect on the voltage and power density of MFC. This paper explored the electrical performance of MFC with potassium permanganate, ferricyanide solution and dissolved oxygen (DO) as cathode electron receivers. The results showed that the internal resistance of MFC with DO depends on catalyst and is higher than that of MFC with potassium permanganate and potassium ferricyanide solution. The maximum volume power density is 4.35 W/m(3), and the smallest internal resistance is only about 54 Omega. In case of DO, the internal resistance and power density is different depending on the catalyst and is not too much related to the membranes. (C) 2010 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.