FT-IR (Fourier-transform infrared) spectroscopy and density function theory (DFT) methods have been applied to the investigation of the interaction of NO and N2O with Fe3+ species in a beta zeolite (BEA). The geometries for H-BEA and Fe-BEA represented as 10T cluster, and NO and N2O adsorption on them in eta(1)-O and eta(1)-N modes have been completely optimized. The results show that NOx could be adsorbed on Fe3+ species and Bronsted acid sites in two modes, but NOx is mainly bonded by N to H or Fe atom and the iron site is preferred. NOx adsorbed on Fe3+ species is more stable than on Bronsted acid sites. Adsorption energies for N2O and NO follow the order of NO > N2O, predicating that the affinity of NO molecule on BEA zeolite is much stronger than N2O molecule on BEA zeolite. (C) 2010 Elsevier B. V. All rights reserved.