A ZnO-resin layer in contact with an Al plate forms a galvanic cell in an electrolyte solution. It is applied to image formation in which the photoconductivity of the ZnO layer is controlled imagewisely by light. In this process called a galvanic cell type electrophotography, the anodic deposit is preferably made of a conductive material rather than an insulating material. Therefore two type developer was prepared and compared, one was NiCl₂ developer, the other was 2, 3, 5-triphenyl tetrazolium chloride developer. Amount of Ni deposited was 50 times more than 1, 3, 5-triphenyl formazan red (TF) deposited at the same exposure, and the quantum efficiency of Ni deposited was up to about 5000. But the optical density of the Ni deposited was less than the TF deposited. This is attributed to a low covering power of Ni. The low covering power of Ni is likely a result of a spherical shape of deposited Ni grains and thus an inefficient light scattering.