Abstract: Copper nanoparticles with uniform size and morphology were prepared on indium tin oxide (ITO) substrates by an electrochemical method. CuSO₄·5H₂O and polyvinylpyrrolidone (PVP) were used as a precursor and a capping agent, respectively. The effect of the concentration of the precursor, the type and concentration of the capping agent, and the potential of electrochemical deposition on the morphology and density of products were studied. A CuO film was obtained by a heat treatment of the as-prepared Cu nanoparticles. Test results show that the CuO film exhibits high photoelectrochemical activity toward water splitting for hydrogen generation.