The inverse gas chromatography method was used for the investigation of the partition and diffusion coefficients of polysulfone and polyetherimide with NMP, gamma -butyrolactone, DMSO, acetic acid, propionic acid, THF, and water over a range of temperature from 200 to 270 degreesC. The weight-fraction infinite-dilution activity coefficients for the solvents, the Flory-Huggins interaction parameters, and the solubility parameters of the polymers are reported.