Hollow SnO2 microspheres with diameters ranging from 300-500 run have been prepared via a simple template-free hydrothermal method in ethanol-water mixed Solution. X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) were used to characterize the hollow microspheres. The gas-sensing properties of the hollow SnO2 microspheres have been investigated. The satisfactory gas response indicated that the hollow SnO2 microspheres have excellent potential application for ethanol sensors.