The absolute free energy of solvation of benzene and perfluorobenzene was measured in supercritical carbon dioxide using the expanded-ensemble method in the context of Monte Carlo (MC) Simulations. The MC calculations were carried out at 12 state points on the solvent phase diagram: (ρ r =0.5, 1.0, 1.5, 2.0; T r =1.01, 1.10, and 1.20). These conditions were chosen to address the accurance of specific molecular interactions between CO 2 and fluorine. The greater stability of perfluorobenzene observed over all states investigated in this study attributed to the greater solvent accessible surface area and 25–30% increase in the strength of the interaction of this molecule with CO 2 in the in-plane part of the first solvation shell, where F atoms exist.