Dynamic response of the micro direct methanol fuel cell (RDMFC) is of significant importance, and has to be considered during cell design as well as operation. In order to explore the effect of design parameter and operating conditions on dynamic behavior, a mu DMFC with stainless steel current collectors as well as stainless steel mesh was fabricated. Different load conditions were applied to the cell to test the effect of stainless steel mesh, cell orientation, methanol concentration and methanol flow rate on transient performance of the cell. A variety of physical and electrochemical processes in the cell are coupled and interactive, which determine that factors affecting transient behavior are complex. But experimental results indicate that methanol crossover through proton exchange membrane (PEM), methanol transportation in anode, removal of CO(2) bubbles and heat loss brought away by methanol solution are four crucial causes influencing dynamic behavior of the cell. (C) 2010 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.