Conventionally, there have been three basic ways of research on H(2) production from H(2)O-splitting with solar energy: photo-catalytic, photo-electrochemical and thermochemical. Among them the thermal dissociation of H(2)O has been considered the most efficient, because it is a single step energy conversion process and gives much higher conversion efficiency than those resulted from other methods. However, the major stumbling block of thermal dissociation of H(2)O has been the requirement of a high dissociation temperature which causes problems both with materials for the reactor and with energy conversion efficiency for the process. In this study, we show that the dissociation temperature can be drastically lowered when H(2)O is thermally dissociated on solid acid materials. A probable mechanism of the thermal H(2)O-splitting on solid acid materials is also presented, based on some experimental results of this study and reports in the literature. Copyright (C) 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.