Zr-MCM-41 was prepared via incorporation of Zr into the amorphous wall of MCM-41 in the hydrothermal synthesis process. Experimentally, photocatalytic generation of hydrogen on Zr-MCM-41 was investigated in a total reflectance system. In the presence of Zr-MCM-41, hydrogen yield (22.4 mumol H-2/h) in the photocatalytic decomposition of H2O was highly enhanced by at least 2.5 times over that of the conventional photocatalyst ZrO2. The enhancement may be due to the high dispersion of ZrO2 and the justified band gap between the conduction band and valance band of ZrO2 in the wall of MCM-41. This work demonstrates how photodecomposition of H2O was affected by high dispersion of photoactive species (ZrO2) in the amorphous wall of MCM-41. (C) 2002 International Association for Hydrogen Energy. Published by Elsevier Science Ltd. All rights reserved.