Structural and optoelectronic properties of as-synthesized SnO2 nanowires were examined in this study. The SnO2 nanowires were first synthesized by thermal evaporation of ball-milled SnO2 powders in argon atmosphere without the presence of any catalysts, and their structural properties are then investigated by X-ray diffraction, Raman scattering, scanning electron microscopy, and transmission electron microscopy. This investigation revealed that the synthesized SnO2 nanowires are single-crystalline and their growth direction is parallel to the [100] direction. In addition, photoresponse of a single SnO2 nanowire was performed with light with above-gap energy, and different characteristics of photoresponses were obtained for the nanowire at ambient atmosphere and in vacuum. The photoresponse mechanism is briefly discussed in this paper. (C) 2004 Elsevier B.V. All rights reserved.