The coupling of the adsorption of humic acids (HA) at 10 mg/l onto Algerian montmorillonite pillared by polyaluminium chloride (Mont-Al-13)to a microfiltration process through a polysulfone membrane leads to total organic carbon (TOC) removal efficiencies close to 60%. A retention of the modified montmorillonite by the membrane barrier of the order of 95% in terms of turbidity suggests better behaviour of the membrane with respect to blocking, which leads to a decrease of the transmembrane pressure. An increase of the pH towards neutrality is observed during the microfiltration process of both HA and the MontAl(13)-HA couple. This increase is found to be independent of the montmorillonite concentration and permeation flux. It seems reasonable to explain this increase by the interactions between the HA and the modified montmorillonite.