The dispersive free energy and acid-base forces of [1-hexyl-3-methylimidazolium hexafluorophosphate] ([HMIM]PF6) were determined by inverse gas chromatography (IGC). Nine nonpolar and polar solvents were used as the probes in the temperature range between (343.15 and 373.15) K. The IGC characterizations encompassed the adsorption thermodynamic parameters, including the standard enthalpy (Delta H-a(s)) and the free energy change of adsorption (Delta G(s)(a)), by using the retention data of different probes at the infinite dilution region. The surface characterization showed that [HMIM]PF6 had a low r(s)(d) value and was a Lewis amphoteric material with a predominantly basic character, as confirmed by the Lewis acidity and basicity constants, respectively.