The inverse gas chromatography (IGC) method was used for the investigation of partition and diffusion coefficients of polymer-solvent systems including polysulfone, polyetherimide, NMP, gamma-butyrolactone, DMSO, acetic and propionic acids, THF, and water over ranges of temperature from 200-270°C. The weight fraction infinite dilution activity coefficients for the solvents, the Flory-Huggins interaction parameters, and the solubility parameters of the polymers were calculated.