A new methodology for the evaluation of the interfacial energy using the Law of Corresponding States is employed here in order to study the behavior of the surface area of pure fluoro carbons and four binary mixtures (CCl4 + CS2, C6H6 + C6H14, H2O + 2-methoxyethanol, and H2O + ethylene glycol) as a function of temperature and composition. The surface tensions of partly halogenated hydrocarbons can be reproduced using a procedure formerly devised for non-polar hydrocarbons. Other polar compounds specially those which contain hydroxyl groups can be evaluated in a similar manner using a slightly different analytical expression. The assumption that a mixture behaves like a pseudo-compound, allows the estimation of the partial molar surface areas of binary mixtures. The dependence of the surface concentration with respect to the partial molar areas is examined for polar and non-polar systems. Arguments are given to estimate the surface concentrations more rigorously than it is usually done. This allows explaining some phenomena that occur in the interface, probably related to the aggregate formation. (c) 2007 Elsevier B.V. All rights reserved.