Different clays have been employed as supports for iron oxide based catalysts prepared by the impregnation method. A basic characterization of the catalysts synthesized has been performed, which includes comparisons between the supports and iron-containing catalysts at bulk and surface levels. The characterization results are correlated with conversion levels achieved during NO, reduction with propene over the iron clay catalysts. Comparison with the catalytic behaviour obtained over an alumina-supported iron oxide catalyst reveals the promising properties of iron clay catalysts for DeNO(x) reactions. (C) 2004 Elsevier B.V. All fights reserved.