The photocatalytic efficiency of colloidal TiO 2 was considerably improved after its immobilization using synthetic layered double hydroxides (LDHs) as support of the photocatalyst. Compared to conventional colloidal TiO 2 nanoparticles (Q-TiO 2 ), LDHs present the advantage to enhance the contact between an organic pollutant and TiO 2 . This work is focused at the same time on the synthesis of new materials (colloidal TiO 2 /LDHs) and to enhance their efficiency for photodegradation in aqueous solutions of selected dye.Q-TiO 2 /Mg 2 AlCO 3 and Q-TiO 2 /Mg 2 FeCO 3 composite photocatalysts were prepared by a direct coprecipitation method at constant pH and characterized by several analytical techniques including XRD, FTIR and BET. Subsequent to the dark adsorption studies, photocatalytic efficiency of the supported catalysts was evaluated using an azo dye, Acid Orange 7, as model compound in an aqueous medium. The supported catalysts exhibit good photodegradation efficiency of this dye and its removal was improved compared to bare colloidal TiO 2 .