An innovative idea of using aluminum as anodes for the combined production of electric energy and hydrogen has been increased in recent years. This study developed a mathematical model for a simplified aluminum-water electrochemical co-generator, a typical type of the combined production systems. A reasonable agreement between the model predictions and experimental data was obtained. Effects of various factors, including the geometric parameters, electrolyte feeding velocity as well as electrode kinetics, were examined for the aluminum-water electrochemical co-generator based on the modeling equations. Some critical values for the future design of the aluminum-water co-generator were proposed. Copyright (C) 2010 John Wiley & Sons, Ltd.