This study has investigated the potential use of acid-activated montmorillonite (AMt) as adsorbent for the removal of 2,4,5-trichlorophenol (2,4,5-TCP) from aqueous solution. The kinetics of adsorption were studied in a batch system. Important parameters which affect the adsorption, such as pH of solution, the mass of acid-activated montmorillonite, temperature and initial TCP concentration have been investigated. The increase in adsorbent mass, pH and temperature resulted in a lower TCP loading per unit weight of the acid-activated montmorillonite, but an increase of adsorption was observed when initial concentration of 2,4,5-TCP increases. The effect of different adsorption parameters was fitted to the pseudo-first-order, pseudo-second-order and the intraparticle kinetic models. The linear regression method was used to obtain the relative parameters. According to the error analysis, it was found that the pseudo-second-order kinetic model was better to predict the experimental results. The value of activation energy was calculated as 47.7 kJ/mol. The result obtained indicates that the adsorption is assigned to a physisorption. (C) 2011 Elsevier B.V. All rights reserved.