The highly crystalline nanoparticles of In0.9Ni0.1TaO4, with a wolframite-type structure, were prepared by a solid-state reaction method. The band gap E-g of In0.9Ni0.1TaO4 is about 2.3 eV, and particles with sizes in the range of 300-500 nm were observed by TEM measurements. We loaded 1.0 wt % partially oxidized nickel as electron-trapping and hydrogen-evolution sites onto the In0.9Ni0.1TaO4 surface from an aqueous Ni(NO3)(2) solution. The TEM measurements show that nearly spherical nano NiOx particles with a size of about 15 nm are distributed on the surface of In0.9Ni0.1TaO4. Stoichiometric amounts of oxygen and hydrogen were evolved under visible-light irradiation using NiOx/In0.9Ni0.1TaO4 with a quantum yield of about 0.66%. This system behaves as a short-circuited microphotoelectrochemical cell. The surface of NiOx is the cathode, and the surface of In0.9Ni0.1TaO4 is the anode.