A new air and water stable metal ionic liquid (IL) PPReO(4) (N-pentylpyridine perrhenate) was synthesized. The density and surface tension of the IL were determined in the temperature range of (293.15 to 343.15) K. The surface entropy of the IL was obtained by extrapolation. In terms of Glasser's theory, the standard molar entropy and lattice energy of the IL were estimated, respectively. Using Kabo's method and Rebelo's method, the molar enthalpy of vaporization of the IL, Delta(g)(1)H(m)(0) (298 K), at 298 K and Delta(g)(1)H(m)(0) (T(b)), at the hypothetical normal boiling point, T(b) = 697 K, was estimated, respectively. According to the interstice model, the thermal expansion coefficient of the IL was calculated, and in comparison with experimental value, it is in good agreement by 4.2 %.