Finally, the new H 3 O + force field allows us to predict the solvation free energy of the proton, H + , as a function of temperature. This provided a validation of the force field by showing that the proton solvation free energy at 298.15 K agrees well with the literature value. Furthermore, our calculations of the intrinsic proton solvation free energy can in principle be combined with temperature-dependent calculations of the Galvani potential to determine its absolute value as a function of temperature. This would enable the estimation of standard chemical potential and enthalpy data for all the ionic species considered in this study, which would be useful in the application of macroscopic thermodynamic models of aqueous solutions containing them.