Inverse gas-liquid chromatography was used with packed columns to measure polyethylene-solvent interactions in polymer solutions of infinite dilution of the solvents. Experimental data are presented for four binary polymer-solvent systems in a temperature range from 40 to 100°C, with different sizes of polymer beads. Solubility and weight fraction activity coefficients of hexane and hexene were calculated. Using concepts from the Prigogine-Flory theory of polymer solutions, Flory-Huggins interaction parameters for the polymer-solvent systems were calculated.