The catalytic reduction behaviors of N2O by CH4 have been investigated over Fe-USY catalyst by examining the influences of CH4, NO, O-2, or their mixtures in detail. The observations show that NO and O-2, which inevitably exist in the gases emitted from industrial sources, such as the nitric acid plant, inhibit the selective catalytic reduction of N2O by CH4 (N2O-CH4 SCR) to some degree, shifting the temperature for >90% N2O conversion to over 450 degrees C. The prohibition of O-2, can be ascribed to its occupying active sites and oxidizing CH4-derived intermediates. The negative effect of NO is very prominent, inhibiting the N2O conversion by strongly occupying the active sites and gradually moving the reaction pathways from N2O-CH4 SCR to NO-assisted N2O decomposition, where the former is more efficient than the latter for N2O decomposition under the same operation conditions. In addition, the amount of reducing agent CH4 has also influenced the N2O conversion profile. (C) 2009 Elsevier B.V. All rights reserved.