An effort has been made to develop a new kind of SnO2-CuO gas sensor which could detect an extremely small amount of H2S gas at relatively low working temperature. The sensor nanomaterials were prepared from SnO2 hollow spheres (synthesized by employing carbon microspheres as temples) and Cu precursor by dipping method. The composition and structural characteristics of the as-prepared CuO-doped SnO2 hollow spheres were studied by X-ray photoelectron spectroscopy, X-ray powder diffraction, scanning electron microscopy, and transmission electron microscopy. Gas-sensing properties of CuO-doped SnO2 hollow sphere were also investigated. It was found that the sensor showed good selectivity and high sensitivity to H2S gas. A ppb level detection limit was obtained with the sensor at the relatively low temperature of 35 A degrees C. Such good performances are probably attributed to the hollow sphere nanostructures. Our results imply that materials with hollow sphere nanostructures are promising candidates for high-performance gas sensors.