Titanate nanotubes were synthesized in hydrothermal treatment of anatase titania powders and concentrated NaOH solution and their structure was investigated. It was suggested that the nanotubes might be constructed from lepidocrocite H(x)Ti(2-x/4)square(x/4)O(4) (x similar to 0.7, square: vacancy) sheets. The newly proposed lepidocrocite titanate nanotube model was supported by X-ray diffraction, electron diffraction, and thermogravimetry studies. (C) 2003 Elsevier B.V. All rights reserved.