The determination of enthalpies of reactions (aqueous and surface complexation) is used in this work to model the temperature effect on the adsorption processes. Microcalorimetry experiments were carried out to determine the enthalpy of adsorption of europium on gamma-alumina at 25 degrees C. The stability constants at 50 degrees C were then calculated with the van't Hoff equation, and a 2-pK approach was used to model the adsorptive behavior of Eu on alumina at 50 degrees C. as a function of pH. The results have shown that the adsorption of Eu3+ on the alumina surface is weakly endothermic. In the experimental conditions considered in the present study, the temperature has only a small effect on the adsorption reaction. (C) 2012 Elsevier Inc. All rights reserved.