The photocatalytic evolution of hydrogen from water was investigated under various conditions over 0.6 wt% Pt-loaded nanocrystalline mesoporous TiO2 photocatalyst prepared by a single-step sol-gel process with a surfactant template. The highly crystalline photocatalyst possessed a mesoporous characteristic with high surface area and narrow monomodal pore size distribution. More specifically, the influence of the following operational parameters; namely sacrificial reagent type, initial solution pH, photocatalyst concentration, initial sacrificial reagent concentration (of the best sacrificial reagent studied), and irradiation time, was the main focus. The hydrogen evolution was experimentally found to be strongly affected by all of the above parameters. The optimum values of initial solution pH, photocatalyst concentration, and sacrificial reagent concentration, as well as the appropriate type of sacrificial reagent, were obtained. The results showed that the utilization of the photocatalyst with the proper selection of optimum operational conditions could lead to considerably high photocatalytic hydrogen evolution activity. (c) 2007 Elsevier B.V. All rights reserved.