A simple physical vapor deposition technique, oxidizing W filaments and in situ evaporating via infrared irradiation heating at 950-1000 degreesC in air, was developed to prepare WO3 one-dimensional nanostructures on Si wafers. Most of the nanostructures were nanorods with polygonal cross-sections, tens of nanometers in width. The nanorods were single-crystalline monoclinic structure, with the axes preferentially aligned along the [1 0 0] or [0 1 0] directions. In addition, some single-crystalline nanobelts of hexagonal structure were formed, with their length directions lying along the [1 1 0] direction. The formation of two different structures is discussed based on their cell parameters. (C) 2002 Elsevier Science B.V. All rights reserved.