It was shown that the adsorption of uncharged particles onto energetically heterogeneous surfaces with Gaussian-like distribution of adsorption energy can be described by the same adsorption isotherm as the adsorption of hydrogen ions from solution onto homogeneous oxide surfaces with surface potentials given by a quasi-Nernst formula. It exemplifies that the separation of electrostatic from energetic factors in the case of ion adsorption onto heterogeneous oxide surfaces is very difficult. Nevertheless, application of calorimetric data for proton adsorption makes it possible to estimate both factors.