This work investigates the use of a commercial clay adsorbent for removing carboxylic acids from model petroleum fractions. The main objective is to emulate the corresponding removal of naphthenic acids from real petroleum fractions. The bulk properties of the adsorbent were analyzed by several physicochemical techniques. The adsorbent capacity of removing three different carboxylic acids was evaluated by conducting equilibrium and kinetics studies in batch systems. A comparison of the performances of different isotherm models indicated that the Brunauer, Emmett and Teller (BET) isotherm is the most adequate model to represent the adsorption equilibrium. A kinetic model using mass balances in the solid and fluid phases presented a good match with the experimental data. The equilibrium results of a model sample were also compared to the removal of naphthenic acids from a real petroleum cut. (C) 2013 Elsevier B.V. All rights reserved.