Among layered semiconductors, tin diselenide (SnSe2) deserves particular attention thanks to its high intrinsic electron mobility (462.6 cm2 V-1 s-1 at T = 300 K) and ultralow thermal conductivity (3.82 W m-1 K-1). So far, some applications of SnSe2 have been proposed in several fields regarding superconductivity, Li- and Na- ion batteries, photodetection, photocatalysis, saturable absorbers for eye-safe lasers and thermoelectricity.In this work we report the gas sensing performances of nanostructured SnSe2 thin film as NO2 (400-800 ppb range) and H2 (10-50 ppm range), operating at low temperature (75-150°C).DFT calculations carried out on SnSe2 demonstrate that, while the stoichiometric single crystal is chemically inert even in air, the non-stoichiometric sample (SnSe2-x , with x~0.3) assumes a sub-nanometric SnO2 surface oxide layer, when it is exposed to ambient atmosphere …