In this paper, an experimental study is performed for hydrogen and oxygen production by new photo-catalytic and electro-catalytic water splitting systems. An effective method for hydrogen production by solar energy without consumption of additional reactants is a hybrid system which combines photo-chemical and electro-catalytic reactions. Experiments are performed in batch and dual cell quasi-steady operation with different light intensities and zinc sulfide photo-catalyst concentrations. The photo-reactor in batch operation achieves 6 mL h(-1) of hydrogen production with 3% w/v of catalyst. The hydrogen production rate corresponds to a quantum efficiency of 75% as measured through illumination of zinc sulfide suspensions in a dual cell reactor. Copyright (C) 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.