BEA zeolite is modified by a two-steps postsynthesis method allowing incorporate iron atoms into the zeolite framework. Two series of the zeolite samples with aluminium (Fe(x)AlSiBEA)and without aluminium (Fe(x)SiBEA), containing various iron content (0.5-4.0 Fe wt.%) are obtained. For low Fe content (<2 Fe wt.%), iron is incorporated into the framework of SiBEA zeolite as a framework pseudo-tetrahedral Fe(III) as evidenced by combined used of XRD, DR UV-vis, XAS, Fe-57 Mossbauer and XPS investigations. In contrast, for higher iron content, the framework pseudo-tetrahedral Fe(III) and an extra-framework octahedral Fe(III) species are identified, For Fe(x)AlSiBEA, significantly higher acidity than for Fe(x)SiBEA is evidenced by FTIR with adsorption of CO and TPD of NH3. Fe(x)AlSiBEA and Fe(x)SiBEA are found to be active and selective catalysts of N2O decomposition and selective catalytic reduction of NO with ammonia. The highest catalytic activity in both processes are obtained for the Fe(4.0)AlSiBEA sample containing iron mainly as the framework pseudo-tetrahedral Fe(III) and characterized by relatively high acidity. (c) 2013 Elsevier B.V. All rights reserved.