A facile reactive-template strategy has been developed to fabricate porous SnO2 nanotubes using MnO2 nanorods as the sacrificial template. The formation of nanotubes is based on the redox reaction mechanism, which requires no post-treatment of the MnO2 templates. The morphological and structural characteristics of the samples have been systematically characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermal-gravimetric (TG), and N2 adsorption-desorption techniques. A gas-sensor device was constructed using as-prepared SnO2 nanotubes and was tested for its ability to detect ethanol and some other compounds. Because of the porous structure and relative large specific surface area, the SnO2 nanotube sensor manifests remarkably improved sensing performance, including fast response recovery, high sensitivity, and excellent repeatability, suggesting the promising application of the SnO2 nanotube materials.