The infrared spectra of trifluoronitrosomethane adsorbed on sublimated sodium chloride films have been spectrophotometrically and thermodynamically characterized. Isotherms were plotted using selected band intensities versus pressure thus allowing for calculation of the heat of adsorption. Using the Brunauer, Emmet, Teller model for physical adsorption, the enthalpy of adsorption calculated was -21 + 5 kJ/mole.