Supercritical Carbon Dioxide: Functions and Applications presents a constructive overview on the use of supercritical carbon dioxide as an alternative solvent to obtain natural products, instead of using conventional organic solvents. The overview includes the fundamentals, industrial applications, and main experimental findings based on recent studies about supercritical extraction using carbon dioxide. Next, the impregnation of polymer materials with two different ketones with known activity against the main pests of stored products (thymoquinone and R-(+)-pulegone) is presented, and the effect of the process variables on ketone loading and the final activity of the impregnated materials is discussed. The authors go on to evaluate the effect of temperature (T: 4169°C) and CO2 density (D: 843957 kg/m3) on the extraction yield of oil and bioactive compounds of N. gaditana using supercritical CO2, a technology that allows for the selective extraction of compounds of interest by varying the pressure and temperature conditions, producing natural extracts without the use of liquid organic solvents. Hydrophobic modifying coatings on textile materials made of polyethylene terephthalate were obtained by precipitating a low molecular weight fraction of ultrafine polytetrafluoroethylene. The modifier application conditions are also defined. The closing chapter provides an overview on the principal applications related to the supercritical fluid extraction of active compounds from tobacco and tobacco waste, emphasizing the influence of the most important processing parameters on the extraction yield.