A novel hollow carbon@SnO2 nanocomposite has been developed via a high cost-effective and facile in-situ etching technique. The as-prepared C@SnO2 product has a high surface area of about 115 m(2) g(-1) and a hollow carbon core, where a lot of SnO2 nanosheets grow onto the carbon shell. Particularly, the silica core as the sacrificial template can be fully removed by hydrofluoric acid (HF) byproduct during the reaction process. Moreover, the deposition of SnO2 sheets and the removal of the silica template can be synchronously performed by a simple one-step process. When applied as the gas-sensing material, the C@SnO2 product manifests highly sensitive and selective to n-butanol. The large surface area, hollow nanostructure and the perfect combination of SnO2 nanosheets and carbon layer contribute to the enhanced gas-sensing performances. The method described in our work can also be employed to design other hollow metal oxides@carbon hybrids for energy storage and catalysis.