Fe-ZSM-5 zeolites of different SUM ratio prepared by means of ionic exchange from aqueous solution and from solid state were used as catalysts for N2O decomposition in the range of temperature from 300 to 500 degreesC. The samples with high iron concentration (3-15 wt.% of Fe), both calcined at 550 and 900degreesC, showed very high activity for N2O decomposition. UV-Vis spectra of iron modified samples have indicated the presence of both the isolated iron species, binuclear complexes and oxide-like phase. Calcination at 900 degreesC resulted in the formation of binuclear iron species and also enhanced the concentration of oxide phase. From IR spectra of adsorbed N2O it was concluded that N2O was bonded to zeolite structure both through the oxygen and nitrogen atoms. (C) 2004 Elsevier B.V. All rights reserved.