Porous clay heterostructures (PCH), obtained on the basis of synthetic saponite, were modified with copper and iron ions by an ion-exchange method and tested as catalysts for the selective reduction of NO with ammonia (NH3-SCR). Transition metal ions were introduced into H+ and NH4+ forms of PCH. The catalysts were characterized with respect to their texture (BET), composition (EPMA), coordination of transition metals (UV-vis-DRS) and surface acidity (FT-IR, NH3-TPD). The PCH-based catalysts have been found to be active, selective and stable in the NH3-SCR process. The Cu-containing catalysts effectively operated at temperatures significantly lower than the Fe-modified samples. The catalyst obtained by exchanging copper ions in the ammonium form of PCH was considerably more active compared to the sample obtained from H+-PCH. (c) 2006 Elsevier B.V. All fights reserved.