A beltlike single-crystalline CdS nanostructure was successfully synthesized by vapor-phase transport of the desired commercial CdS powder at 850degreesC. Its morphology and microstructures were determined by X-ray powder diffraction, scanning electron microscopy, and transmission electron microscopy. The observations reveal that the products consist of a large quantity of beltlike nanostructures with typical lengths in the range of several tens to several hundreds of micrometers. The typical widths of CAS nanobelts range from several tens to several hundreds of nanometers. The as-synthesized semiconductor CdS nanobelts are pure, structurally uniform, and single crystalline. CdS nanobelts, which have a rectangle-like cross section, could be an ideal system for building nanometer-scale optoelectronic devices along individual nanobelts, such as laser light-emitting diodes and optical devices.