A thermodynamic model for the size dependence of enthalpy of condensation, Delta H-con, is discussed. The model is valid over a range of radii where the arrangement of surface layer and surface tension remain invariable; it provides a way of calculating enthalpy and entropy changes and equilibrium vapor pressures. The difference between Delta H-con for two liquid bodies of the same chemical nature is equal to the variation of the autoadsorption energies on their surfaces.