This presentation is focused on the use of ionic liquids as coatings for microcantilever transducers with the objective to achieve selective detection of air and water quality parameters through micro-electro-mechanical-systems (MEMS) based sensors. Ionic liquids offer advantages of stability due to extremely low vapor pressure and selective uptake of analytes from the atmosphere or from aqueous solutions. Methods have been devised to reproducibly apply a coating of a selected ionic liquid on the surface of a microcantilever transducer and test the response of the cantilever in terms of bending and/or changes in oscillation frequency. Through a calibration procedure, the response can be translated into concentration of the analyte, and from the responses of arrays of microcantilevers, the concentration of mixtures can be obtained. In this work, the goal was to demonstrate the principle that ionic liquid coatings can be used as coatings for MEMS sensors. To achieve this goal, we first identified the desired properties of ionic liquids for this application. Then, a method was developed to apply coatings of the selected ionic liquid on microcantilevers. The response of coated cantilevers was tested for various vapor analytes including water, acetone, and ethanol. The results of these tests were very encouraging and led to subsequent measurements with real atmospheric contaminants such as NOx, ozone, and CO2. The results have shown that ionic liquid coatings are suitable for microcantilever response of atmospheric and aqueous contaminants.