Using infrared irradiation to heat a Mo foil in a moderate vacuum (5 Torr), quasi-aligned MoO3 nanotubes, about 5-8 mum long, were prepared on a Ta substrate. Most of the nanostructures show polygonal morphology with a hollow core in cross-sections. The width of nanotubes range from 50 to 300 nm, and the hollow core are about 20-150 urn in diameters. The nanotubes possess orthorhombic single-crystal structure and have preferentially grown along the [10 0] direction. Stacking faults normally form on the (020) planes, resulting from the layered structures. (C) 2002 Elsevier Science B.V. All rights reserved.