In this work, the adsorption of 2,4-dichlorophenoxyacetic acid (2,4-D) on activated carbon derived from date stones (DSAC) was studied with respect to pH and initial 2,4-D concentration. The experimental data were analyzed by the Freundlich isotherm, the Langmuir isotherm, and the Temkin isotherm. Equilibrium data fitted well with the Langmuir model with maximum adsorption capacity of 238.10 mg/g. Pseudo-first and pseudo-second-order kinetics models were tested with the experimental data, and pseudo-first-order kinetics was the best for the adsorption of 2,4-D by DSAC with coefficients of correlation R-2 >= 0.986 for all initial 2,4-D concentrations studied. The results indicated that the DSAC is very effective for the adsorption of 2,4-D from aqueous solutions. (C) 2008 Elsevier B.V. All rights reserved.