A simple, intuitive and computationally non-intensive modified model, proposed first for the prediction of the catalyst basicity of binary mixed oxides, based simply on the chemical composition using the Sanderson Method was extended to ternary systems. The modification of the method allows the discrimination between the oxygen charge on different chemical environments (differences between local and global composition). TPD-CO2 result was used to the validation between theoretical values and experimental results, letting us propose a correlation between the oxygen charge of the different clusters and the TPD-CO2 peak maxima.