Photocatalytic water splitting is a process which could potentially lead to commercially viable solar hydrogen production. In order to evaluate if solar concentration could be used to increase the feasibility of the process, the effect of light intensity on photocatalytic water splitting was examined. Degussa P25 TiO2 films were used to form a photocatalytic cell and illuminated with a Xenon arc lamp at intensities up to 52 suns. The reaction demonstrated a sub-linear relationship where photocurrent was proportional to intensity with an exponential value of 0.627. This is an important finding for photocatalytic water splitting. It could provide an avenue for the development of a large scale photocatalytic water splitting system for hydrogen production and the further commercialisation of this technology. Copyright (c) 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.