Bi2Se3 nanobelts with a typical width of 20-80 nm, thickness of 8-10 nm and length of several micrometers have been successfully synthesized. Synthesis was carried out using a simple co-reduction method under ultrasonic irradiation for 15 h at room temperature. The product was characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), electron diffraction (ED), and high-resolution transmission electron microscopy (HRTEM). The results indicate that the Bi2Se3 nanobelts are well-crystallized nanocrystals and grow along the (001) direction. The morphology and size of the nanostructures vary with synthesis temperature. A possible formation mechanism of Bi2Se3 nanobelts is proposed: (C) 2004 Elsevier B.V. All rights reserved.