In the last few years, cationic layered clays, including bentonites have been investigated as potential catalysts for SCR DeNOx systems. In this work, bentonite as the representative of layered clays was modified in order to obtain an alternative, low-cost NH3–SCR catalyst. Samples of raw clay were activated with HCl or HNO3, treated with C2H2O4 and subsequently pillared with alumina by the ion- exchange. Afterwards, the modified materials were impregnated with iron and copper. The obtained catalysts were characterized by XRD and FT-IR. SCR catalytic tests carried out over analyzed samples indicated the conversion of NO of approximately 90% for the most active sample. The type of acid used for modification and the type of active phase strongly influenced the catalytic properties of the analyzed materials.