In this paper we show that the approach called surface tension components theory, developed to interpret contact angle phenomena, has been established on an oversimplified thermodynamic basis. It is recalled that it is possible to separate enthalpies into components, even in the surface case, but that it is not straightforward to apply these equations to the free enthalpies, even at constant temperature and pressure. Some new results have been utilized to show that it is possible to use same approximations at ambient temperature, and therefore to use surface tension component theory in some cases with fruitful results, However, a new approach called surface enthalpy components theory seems better, from both the theoretical and the experimental standpoints.