An ionic liquid (IL) C6MIGaCl4 (1-methyl-3-hexylimidazolium chlorogallate) was prepared by directly mixing GaCl3 and 1-methyl-3-hexylimidazolium chloride with molar ratio of 1/1 under dry argon. The density and surface tension of the IL were determined in the temperature range of 283.15-338.15 K. The ionic volume and surface entropy of the IL were estimated by extrapolation, respectively. In terms of Glasser's theory, the standard molar entropy and lattice energy of the IL were estimated, respectively. By use of Kabo's method, the molar enthalpy of vaporization of the IL, Delta H-g(l)m(0) (298 K), at 298 K was estimated. According to the interstice model, the thermal expansion coefficient of IL C6MIGaCl4, alpha, was calculated and in comparison with experimental value; their magnitude order is in good agreement.