The inverse gas chromatography technique (IGC) was used to determine the partition and diffusion coefficients of several solvents in two polymers at infinite dilution of the solvent. The two polymers were styrene-acrylonitrile (SAN) and polybutadiene (PBD); the solvents were ethylbenzene, acrylonitrile, and styrene. Experiments were performed over a temperature range of 150 to 225°C for the SAN systems and 50 to 125°C for the PBD systems. Results for the thermodynamic and transport data presented and discussed.