Microwave radiation can effectively heat chemical reactors in which bulky, branched and polycondensed naphthenes convert into the appropriate aromatics at atmospheric pressure. Two types of catalysts, traditional Pt/C and bifunctional Ni-silica-alumina, were used for dehydrogenation of naphthenes under microwave radiation. From the dehydrogenation reaction in microwave mode and in conventional heating mode, it was found that the catalytic activity in microwave mode increased more greatly than that in conventional heating mode at the same reaction temperatures. Such an effect may result from the fact that the temperature of the metal particles (Pt, Ni) in microwave mode is higher than the average temperature of the catalyst bed in thermal mode. (C) 2008 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.