A series of ZnO/CdS photoelectrodes with three-dimensional (3-D) structure were synthesized by two-step hydrothermal method. The photoelectrodes were characterized by x-ray diffraction, UV–vis absorption spectrum, and field emission scanning electron microscope. The results confirmed that all samples have similar hierarchical structure composed of CdS sheets and ZnO nanorod. In particular, the sample fabricated by the CdCl₂ precursor as the Cd source gave the wider band gap and more porous structure. The photoelectrochemical performance of the samples was estimated by photocurrent density testing in the solution under irradiation. The sample prepared by the CdCl₂ precursor exhibited higher photocurrent density than the other three samples due to its 3-D structure, wider band gap, and more porous morphology.