This work investigated the equilibrium batch dynamics of using olive oil mill solid residues as an adsorbent for zinc removal from aqueous solutions. It was found that a sorbent concentration of 4 g L-1 achieved the best removal percentage and the best sorbent capacity. Adsorption equilibrium was reached in 60 min for an initial zinc concentration of 0.25 mmol/L and 180 min for an initial zinc concentration of 1-3 mmol/L A particle size of olive mill residue ranging from 0.85 to 1.18 mm was used in the study. It was found that the maximum adsorption capacity of zinc was at a pH value of 5.0. It was found that q(max) for zinc ions, was 5.63, 6.46, and 7.11 mg g(-1) at temperature values of 298, 308, and 328 K, respectively. The data pertaining to the sorption dependence upon metal ion concentration could be fitted to a Langmuir isotherm model. The second-order kinetic model provided the best correlation of the data. The change in entropy (Delta S degrees) and heat of adsorption (Delta H degrees) for zinc ions adsorption on olive mill solid residues were estimated as -1419 kJ kg(-1) K-1 and 4.7 kJ kg(-1), respectively. The examined low-cost adsorbent could offer an effective way to decrease zinc ions concentration in wastewater. (C) 2009 Elsevier B.V. All rights reserved.