Most of the recent research work on layered chalcogenides is understandably focused on single atomic layers. However, it is uncertain if the single layer units are most ideal structures for enhanced gas-solid interactions. To probe this concern, we have synthesized few layer thick SnSe2 nanosheets ink using liquid exfoliation method. The morphology, thickness / layering and elemental analysis of the sheets were characterized by using SEM, TEM, AFM, Raman spectroscopy and by XPS. The two dimensional (2D) SnSe2 nanosheets sensor device with different thicknesses was assessed for the humidity and gas sensing performances with exposure to humidity in different conditions. The results show that compared to the bulk / thicker counterpart, sensor device of few SnSe2 layers exhibit excellent sensitivity, recovery and ability to be tune the sensing performance with thickness and can be used in lab on chip devices.