Two compact plate methane steam reformers, consisting of closely spaced plate electrically heated alumite catalysts, have been numerically investigated in the relation to heat and mass transfer. Based on the ordinary heat exchange reformer (HER), where endothermic and exothermic reactions take place in alternative chambers, a developed heat exchange reformer coupled with preheating chamber (PHER) is proposed by integrating a preheating chamber with a combustion chamber. The simulation results predicted that the PHER could be started by electrical heating through a catalyst at the beginning, even with the inlet combustion gas temperature of 298 K, whereas the HER requires a combustion inlet temperature as high as 723 K, which showed the PEHR high potential for simplifying the heat exchange network in a fuel processor. On the other hand, the compact structure of the reformer could constitute a single unite of reformer, which is easy to be placed and scaled up. (C) 2008 American Institute of Chemical Engineers.