The semiconducting properties of the heterojunction CuO/ZnO, synthesized by impregnation method from nitrates, are studied for the first time to assess its feasibility for the hydrogen production under visible light, an issue of energy concern. CuO exhibits a direct optical transition at 1.33eV, due to Cu2+: 3d orbital splitting in octahedral site, and possesses a chemical stability in the pH range (4-14). The Mott-Schottky plot in (Na2SO4, 0.1M) medium indicates p-type conduction with a flat band potential of 0.70V(SCE) and a holes density of 1.35x10(17)cm(-3). As application, hydrogen evolution upon visible light is demonstrated on the heterojunction x%CuO/ZnO (x=5, 10 and 20wt.%). The best performance occurs at pH similar to 12 with an evolution rate of 4.8cm(3)min(-1) (gcatalyst)(-1) and a quantum yield of 0.12%. The improved activity is attributed to the potential of the conduction band of CuO (-1.34V(SCE)), more negative than that of ZnO, the latter acts as electrons bridge to water molecules. The presence of SO32- reduces the recombination process, thus resulting in more H-2 evolution. Copyright (c) 2015 John Wiley & Sons, Ltd.