SnO2 nanotubes have been prepared via a facile hydrothermal method at low temperatures using polycarbonate (PC) membrane as a hard template. The walls of as-prepared SnO2 nanotubes are composed of fine nanocrysalline particles and the size of SnO2 nanocrystals could be modified by changing reaction temperature. Formation mechanism of SnO2 nanotubes is also discussed according to the experimental results. Cathodoluminescence properties of the SnO2 product indicated that the band gap of the nanostructures increase from 3.75 eV with a particle size 5.6 nm to 3.99 eV with a particle size 3.3 nm. The as-prepared SnO2 nanotubes were found to show enhanced gas-sensing activity and may be used as a candidate for the fabrication of gas sensors.