High-purity single crystal ZnO nanowires were synthesized by the thermal decomposition of zinc acetate dihydrate at 300 degrees C in air for 3 h without a catalyst. The zinc acetate dihydrate was characterized by thermogravimetric-differential scanning calorimetry and mass spectrometry (TG-DSC-MS) to determine the thermal decomposition and crystallization temperature. Results reveal that the ZnO nanowires were produced through a dehydration, vaporization/decomposition, and deposition/formation process, which differs from the common vapor-liquid-solid (VLS) mechanism. X-ray diffraction demonstrates that the ZnO nanowires have a wurtzite crystal structure, and scanning electron microscopy shows their diameter and length to be about 40 nm and a few micrometers, respectively. High-resolution transmission electron microscopy reveals that the nanowires are of a single crystal, which grew in the [001] direction. In addition, photoluminescence spectra results of the as-grown ZnO nanowires suggest possible applications in ultraviolet emission devices. (C) 2008 Elsevier B.V. All rights reserved.