Membrane electrode assembly (MEA) after hot pressing could not achieve its best performance before activated properly because the passages for protons electrons reactants and products in the MEA are not constituted completely In this research effective multi step activation for MEA was proposed and the mechanism was discussed The process includes three steps methanol activation at room temperature forced activation at intermediate temperature and proton activation at intermediate temperature The performance of the MEA was correspondingly improved and reached respectively 54 mW cm(-2) 61 mW cm(-2), 78 mW cm(-2) after each step of the activation Apparently the performance was greatly enhanced by multi step activation The activation process of MEA is not only a process of the humidification of the proton exchange membrane but also a complex process for the establishment of the channels for electrons ions gases and liquids Furthermore the conduction of electrons ions and the transportation of the reactants and products are enhanced while the micro structure of the MEA is kept stable (C) 2010 Professor T Nejat Veziroglu Published by Elsevier Ltd All rights reserved