A method has been developed to synthesize metal and metal oxide nanostructures in high yields on the surface of SiO 2 /Si substrate. In this method, starting materials in a covered alumina crucible are thermally evaporated under a high vacuum or a low pressure of ambient air. Spherical gold nanoparticles with a size of 15nm and nanowires with a diameter of 70nm were synthesized. SnO 2 rough microwires, smooth nanowires, and nanoknives were synthesized by using Sn granules, SnO powder, and SnO 2 powder as source materials, respectively. The microwires showed a quadrangular cross section and a length of several microns, while the nanowires showed a circular cross section and approximately the same length. The effects of source temperature and deposition time on nanostructure growth were studied. X-ray diffraction patterns suggested that the as-synthesized products consisted of crystalline nanostructure. Nanocomposite gas sensors on the base of noble metal and metal oxide were fabricated. These SnO 2 nanowire gas sensors showed a reversible response to dilute NO 2 gas at operating temperatures ranging between room temperature and 300°C even at high concentrations. The results demonstrated that gold doping improved the sensor response.