By using literature surface tension data for a heterogeneous set of 110 binary liquid mixtures, it is shown how the analytical expression provided by the Extended Langmuir model is able to describe most of the different possible behaviours found, by means of just one or two adjustable parameters. For every system four plots, all of them providing complementary information to each other, are employed to discuss the parameters values obtained from the fitting of data, in terms of the two contributions considered by the model: the effect that heteromolecular interactions into the mixture have on the surface tension, and the prevalent adsorption of one compound to the surface phase. (c) 2005 Elsevier B.V. All rights reserved.