Nanocrystalline bismuth telluride (Bi2Te3) a promising thermoelectric material, was successfully prepared by a hydrothermal method. The products were characterized by means of X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectrum and inductively coupled plasma-atomic emission spectrometer. The result shows that the Bi2Te3 crystals have diameters ranging from 20 to 25 nm with high purity. The reaction mechanism and influence of temperature and time on products are discussed. (C) 2004 Elsevier B.V. All rights reserved.