The galvanic contact deposition of ZnO was carried out by immersing a conductive substrate short-circuited with a Zn rod into O-2-saturated aqueous Zn(ClO4)(2) solutions, and the deposition behaviors were investigated in comparison with that in Zn(NO3)(2). The dissolution of the Zn rod in the Zn(ClO4)(2) solutions supplied a continuous and almost constant current to the substrate, allowing the cathodic electrodeposition of ZnO without an external power and by-products. The morphology of the resulting ZnO depended on the Zn(ClO4)(2) concentration. In contrast, a much smaller current was observed in the Zn(NO3)(2) solution, and little ZnO was deposited.