During the last decades, many fields (e.g., from disease diagnostics to environmental monitoring and from industrial process control to safety systems) have had increased demand for highly sensitive, small size and portable gas-sensing devices. In this scenario, metal-oxide based chemiresistive gas sensors, which responses depend on the change in their electrical conductance upon interaction with the target gas, have been widely studied and commercialized. Tin oxide (SnO2) is one of the widely used and most important metal-oxide semiconductor used in gas sensors mainly due to its sensitivity to different gaseous species. Metal oxide nanowires have demonstrated improved properties compared to the conventional thick film gas sensors mainly due to their huge surface-to-volume ratio, which leads to improved gas response.