Abstract: Vegetable oils refining process purpose is the removal of free fatty acids, phospholipids, trace of metals, peroxides, aldehydes, carotenes, sterols and others compounds, that affect the flavor or oxidative stability of the refined oil. Among these compounds, Free Fat Acids (FFA) may be used in the food, cosmetic and pharmaceutical industries in its original composition or as derivatives. Nevertheless, during the refining process of crude vegetable oils, chemical and thermal decomposition or separation of the most valuable substances occur, including the Free Fat Acids (FFA). In this work, the isotherms of Langmuir and BET has been used to modeling the adsorption capacity of FFA of the crude palm and andiroba oils adsorbed on thermally activated γ-alumina AG.450 and on γ-alumina AG.650, obtained from consecutive bath adsorptions experiments. Additionally, experiments varying the adsorption time, from 1-30 min, permitted the adsorption kinetic study by one second-order model. The results has been analyzed by the correlation coefficients and errors of the predict versus experimental data of FFA capacity on γ-alumina, demonstrating the high accuracy of the model applied.