Abstract: A Moroccan Benonite taken from a geological site in the North-Eastern Rif of Morocco has been characterized by XRF, CEC measurements, XRD, IRTF, SEM and N2 adsorption/desorption at -196 °C. The results showed that the structure of the purified bentonite (PB) is constituted exclusively of monmorillonite and some Mg2+ and Fe3+ cations replace Al3+ in the octahedral sheet. The specific surface area developed is of 74 m2 g-1, and the diameters of pores are superior to 38 Å indicating the presence of mesopores. The adsorption study of methylene blue (MB) onto PB showed that the percentage removal of this molecule can reach 99.6%, and the amount of MB adsorbed depends closely on adsorbent dosage, pH and solution temperature. The results of the adsorption tests showed that the experimental data fitted very well the pseudo second order model. Also, it was found that for temperatures ≤ 45 °C, the adsorption process proceeds by surface adsorption followed by an internal diffusion into the particles with Ea=49.7 kJ.mol-1; while for temperatures ≥ 55 °C, it is governed by an internal diffusion into the particles with Ea = 2.3 kJ.mol-1. The low Ea values are characteristic of physical adsorption.