Some modifications of a mechano-catalyst, Cu2O, and optimization of the reaction conditions were attempted to improve its activity for mechano-catalytic overall water splitting. The rates of evolution of H-2 and O-2 were improved by deposition of nafion onto Cu2O and the choice of an appropriate stirring rod. The irradiation of visible light (lambda > 550 nm) was found to maintain the activity in the time course, which gradually decreased without irradiation.