The retention diagrams of benzene, toluene, ethyl benzene, chloro benzene, n-propyl benzene, isopropyl benzene, methyl acetate, ethyl acetate, n-propyl acetate, n-butyl acetate and isoamyl acetate on the polycaprolactone were plotted at temperatures between 70 and 140degreesC by inverse gas chromatography technique. Percent crystallinity of polycaprolactone were obtained at temperatures below melting point from the retention diagrams of benzene, toluene and ethyl benzene. It was concluded that the data obtained by inverse gas chromatography were comparable those of obtained by differential scanning calorimetry. Specific retention volume, V-g(o), Flory-Huggins polymer-solvent interaction parameters, chi(12)infinity, the weight fraction activity coefficients of the solvents at infinite dilution, Omega(1)(infinity), effective exchange energy parameters, X-eff were determined. Later, the partial molar heat of sorption, DeltaH(1,sorp) and the partial molar heat of mixing, DeltaH(1)(infinity) were obtained from the slope of the logarithm of specific retention volume, Ln V-g(o) versus 1/T plot and from the slope of the logarithm of the weight fraction activity coefficients, Omega(1)(infinity) versus 1/T plot, respectively.