In order to form nanowire (NW)-based p-n junctions, vertically-aligned ZnO-CuO hybrid NW arrays were synthesized by a two-step thermal chemical vapor deposition process. The diameter of parallel-connected ZnO and CuO NWs were estimated to be 146 +/- 12 nm and 55 +/- 11 nm, respectively, as observed by scanning electron microscopy. Chemical and structural characterizations of ZnO-CuO hybrid NW arrays were performed using X-ray photoelectron spectroscopy and X-ray diffraction, resulting in the formation of high-quality hexagonal ZnO and monoclinic CuO NWs. The temperature dependence of I-V curves and impedance spectra suggested that clear rectifying behavior related with thermionic emission of carriers and the presence of an electrical potential barrier between the ZnO and CuO NWs. (C) 2015 Elsevier B.V. All rights reserved.