ZnO nanorod arrays have been grown on glass substrates. X-ray diffraction demonstrated that most of the nanorods in the arrays are of wurtzite crystal structure with preferable [0 0 1] growth direction. The morphology and the microstructure of the arrays and the nanorods were investigated by using scanning electron microscopy and transmission electron microscopy. A wetting layer of ZnO was observed between the nanorods and the substrate. On the (0 0 1) surfaces of some nanorods, the initial stage of nucleation and the subsequent development of the nuclei were observed, revealing the process of the nanorod growth. Electron energy-dispersive X-ray spectroscopy revealed that the wetting layer and the nanorods exhibit different stoichiometric ratio. The kinetics of the formation of the structures was discussed within the framework of the Stranski-Krastanov mechanism. In addition, photoluminescence spectra of the as-grown ZnO nanorod arrays indicate their possible applications in ultraviolet (UV) emission devices. (C) 2004 Elsevier B.V. All rights reserved.