Hexagonal CdS nanotubes with external diameter of 25-125nm and wall thickness of 10-15nm were obtained through surfactant-free route. The reactions were completed under ultrasonic irradiation in aqueous solution at room temperature. The products were characterized with X-ray powder diffraction, transmission electron microscopy and high-resolution transmission electron microscopy. (C) 2003 Elsevier B.V. All rights reserved.