Nonaqueous room temperature ionic liquids (RTILs) offer a new method of using electrochemical impedance spectroscopy (EIS) to analyze coatings without the confounding effects, such as plasticization, associated with an aqueous working fluid(1). Thermal cycling has been used as an accelerated testing method for ranking the corrosion protection of coatings(2,3). The influence of thermal cycling on the degradation of a coating was investigated using a hydrophilic RTIL as the electrolyte for EIS experiments. The change in diffusion coefficient, saturated water volume fraction and activation energy for the absorption and desorption of water by the coating was obtained. copyright The Electrochemical Society.