The United States Environmental Protection Agency (EPA) classified the phenylurea herbicide Diuron (C₉H₁₀Cl₂N₂O) as possibly carcinogenic to humans. This research is focused on the adsorbent performances of a Algerian sodium Montmorillonite (Mont-Na), for the removal of Diuron in aqueous solutions. The material is characterised before and after processing using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), specific surface area (S_BET) and thermal analysis (TGA/DTA). The tests were firstly realised at 25°C and pH = 6.3. Until 61 hours of experiment, no removal was obtained in this case. After that, the experiments were carried out on Mont-Na at high temperature and medium pH (T = 45°C, pH = 6.3) and then at ambient temperature and basic pH (T = 25°C, pH = 11). The removal was increased from 74% to 91%, respectively. The equilibrium is reached after 5 hours and the adsorption capacity is between 0.74 mg/g at 45°C and 0.91 mg/g at pH = 11. The kinetic modelling shows that the pseudo-first order describes the experimental data of the Diuron adsorption on Mont-Na and the equilibrium data are modelled perfectly by applying the Elovich model. The thermodynamic quantities indicate that the adsorption process on Mont-Na at pH = 6.3 is spontaneous (ΔG < 0) and endothermic (ΔH = 31.80 kJ.mol⁻¹). In conclusion, under the operating conditions used, local Mont-Na proved to be an excellent material for the adsorption of Diuron in aqueous solutions. That could be very promising for sewage treatment.