The high pressure inverse gas chromatography technique was used to study the effect of carbon dioxide on the solubility and diffusivity of dichloromethane in polyetherimide. CO2 was used as the carrier gas with pressures from 0.7 to 3.5 MPa and temperatures between 100 and 175 degrees C. Similar data were obtained for the dichloromethane-polyetherimide system using helium as the inert carrier gas. As a result of less favorable thermodynamic interactions between the polymer and solvent, the solubility of the dichloromethane was found to be decreased appreciably in the presence of CO2. The increased free volume in the polymer provided by the dissolved CO2 significantly increased the diffusion coefficient. When the temperature was increased the solubility was decreased while the diffusivity was increased. These behaviors have the potential to considerably improve devolatilization processes. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 114: 2497-2501, 2009