This paper proposes anew methodology for the modification of clays with the mixed Al-Fe and Al-Ce-Fe systems, which involves the synthesis of solid polymeric precursors and their use as pillaring agents in the modification of clays. The process of intercalation of clay with Al-13, Al-13 + Fe and Al-13 + Ce + Fe nitrate was performed using ultrasound. The pillaring agents Al-13, Al-13 + Fe and Al-13 + Ce + Fe were characterized by XRF, XRD, SEM and Al-27 NMR techniques, and pillared clays were characterized by XRF, XRD and N-2 adsorption to 77 K. The catalytic properties of pillared clays were evaluated using catalytic wet peroxide oxidation of phenol in dilute aqueous medium, demonstrating activity comparable to that of solids modified by the conventional method. (C) 2009 Elsevier B.V. All rights reserved.