Natural montmorillonite (Wyoming, A-15) was pillared with alumina, titania or zirconia and then modified with copper or iron introduced by the ion-exchange method. The synthesized samples were characterized by XRF (composition), XRD (structure), BET (texture) and tested as catalysts for selective reduction of NO by ammonia. The highest activity in the NO SCR process was found for the TiO2-intercalated clay doped with copper or iron. The NO and NH3 chemisorption sites were studied by temperature programmed desorption of NO or NH3 as well as FT-IR spectroscopy. (C) 2004 Elsevier B.V. All rights reserved.