This paper reports on the performance of an alkaline-acid direct ethanol fuel cell (AA-DEFC) that is composed of an alkaline anode, a membrane and an acid cathode. The effects of membrane thickness and the concentrations of various species at both the anode and cathode on the cell performance are investigated. It has been demonstrated that the peak power density of this AA-DEFC that employs a 25-mu m thick membrane is as high as 360 mW cm(-2) at 60 degrees C, which is about 6 times higher than the performance of conventional DEFCs reported in the literature. Copyright (C) 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.