Removal of a synthetic organic herbicide, metsulfuron-methyl (MSM), from aqueous solutions has been studied in batch and stirred tank adsorbers charged with granular activated carbon particles. Two kinetic parameters, film mass transfer and intraparticle diffusion coefficients, were estimated from concentration decay curves obtained in the batch adsorber. Based on these kinetic parameters, the concentration profiles measured in the stirred tank adsorber were simulated. From experimental and simulated results, it was proven that the film mass transfer at external surfaces of carbon particles controls the overall mass transfer, particularly at low mixing (rotation of blades), during the adsorption of MSM by granular activated carbon particles.