CeO₂decorated SnO₂hollow spheres were successfully synthesized via a two-step hydrothermal strategy. The morphology and structures of as-obtained CeO₂/SnO₂composites were analyzed by various kinds of techniques. The SnO₂hollow spheres with uniform size around 300 rim were self-assembled with SnO₂nanoparticles and were hollow with a diameter of about 100 nm. The CeO₂nanoparticles on the surface of SnO₂hollow spheres could be clearly observed. X-ray photoelectron spectroscopy results confirmed the existence of Ce³⁺and the increased amount of both chemisorbed oxygen and oxygen vacancy after the CeO₂decorated. Compared with pure SnO₂hollow spheres, such composites revealed excellent enhanced sensing properties to ethanol. When the ethanol concentration was 100 ppm, the sensitivity of the CeO₂/SnO₂ composites was 37, which was 2.65-times higher than that of the primary SnO₂hollow spheres. The sensing mechanism of the enhanced gas sensing properties Was also discussed.