SnO2 nanowires (NWs) have been directly synthesized in high-yield on the surface of Au-coated Sn grains using a water-assisted chemical vapor deposition (CVD) method. The Au-coated Sn grains served themselves as both the Sn source, which reacted with H2O vapor at 700-800 degrees C under the flow of high purity N-2 carrier, and the substrate for the growth of the SnO2 NWs. The synthesized SnO2 NWs were systematically studied using X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Raman spectroscopy. The single-crystalline SnO2 NWs are about 100-150 mu m in length and 16-60 nm in diameter, which can be tuned by simply adjusting the CVD temperature. A possible formation mechanism of SnO2 NWs was proposed and discussed. Gas sensors based on SnO2 NWs prepared at 800 degrees C exhibited excellent sensing performance, characterized with excellent selectivity and fast response time to ethanol vapor and H2S gas operating at 320 degrees C. (C) 2009 Elsevier B.V. All rights reserved.