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The properties of tin containing MFI type zeolite nanocrystals (Sn-MFI) synthesized under hydrothermal conditions from colloidal suspensions, and further application for selective detection of automotive exhaust gases (CO, CO 2 , NO x ) are reported. The properties of the Sn-MFI nanosized zeolite are compared with the pure silicalite-1 nanocrystals (Si-MFI) synthesized under identical conditions, and used as a reference. Additionally, both samples (Si-MFI and Sn-MFI) with high crystallinity and high porosity were stabilized in coating suspensions and deposited in films by spin-coating approach. The Si-MFI and Sn-MFI samples as self-supported pellets and thin films were exposed to different concentrations of exhaust gases in the presence of 100 ppm of water. The sorption behavior of the Sn-MFI and the Si-MFI towards CO, CO 2 , NO and NO 2 gases was followed by in situ IR spectroscopy. The influence of the tin concentration in the zeolite nanocrystals and the type of assembly (self-supported pellets and films) on the gas detection was studied. The fast detection of NO 2 with the Sn-MFI sample in comparison to the other gases implies that the tin containing zeolite could be considered for further use a selective material for detection of low concentrations of NO 2 (0–20 ppm).