In this study, adsorption of boron onto Siral 5, Siral 40, and Siral 80 samples was studied in a batch system with a function of temperature and contact time. The results of adsorption studies indicate that adsorption process was well described with the Freundlich equation and Dubinin-Radushkevich (DR) equation. The Langmuir model does not appear to fit the adsorption better than Freundlich or DR. It has also been found that the magnitudes of free energies are less than 8 kJ mol(-1) and within the energy range of physical adsorption. The intraparticle diffusion model and pseudo-first-order and pseudo-second-order kinetic model were tested to find out rate constants of adsorption. From kinetic experiments, it is realized that boron adsorption onto Siral samples obeyed the pseudo- second-order kinetic model. The thermodynamic studies showed that adsorption process was not spontaneous nature and endothermic. It could also be added that the randomness increased during the adsorption. (c) 2005 Published by Elsevier Inc.