In this work, the removal of a beta-blocker, atenolol, and a pesticide, isoproturon, from aqueous solutions by adsorption on granular activated carbon fixed-bed columns has been studied. The effect of important operation parameters on breakthrough curves as column length (Z = 1.0-3.0 cm), initial concentration of atenolol or isoproturon (C-0 = 50.0-500.0 mu g.L-1),and volumetric flow rate (Q = 1.5 mL.min(-1)) was studied. Breakthrough time of the bed was found to increase with an increase in the value of the column length, and with a decrease in the value of initial concentration or flow rate. Mathematical models, as Bohart-Adams, Thomas, Yoon-Nelson, and Clark were applied to the experimental data for the prediction of the breakthrough curves, and to determine the characteristic parameters of the bed.