Mechanistic and kinetic aspects of direct N2O decomposition over BaFeAl11O19 hexaaluminate were investigated in the Temporal Analysis of Products (TAP) reactor and compared with those previously determined for Fe-MFI zeolites. The catalysts were chosen due to their de-N2O operation in significantly different temperature regimes. Several micro-kinetic models were evaluated for describing the transient responses of N2O, N-2, and O-2 obtained in N2O pulse experiments at 823-973 K. Thorough discrimination between these models enabled us to conclude that the preferred models of N2O decomposition over BaFeAl11O19 and Fe-MFI zeolites differ in the reaction pathways leading to O-2 and N-2. Gas-phase N-2 and O-2 are simultaneously formed over BaFeAl11O19 upon interaction of gas-phase N2O with a bi-atomic surface oxygen (*-O-2) species. Contrarily, the formation of O-2 over Fe-MFI occurs via a sequence of three elementary heterogeneous steps and limits the overall rate of N2O decomposition. Despite the easy O-2 formation. BaFeAl11O19 is less active for N2O decomposition below 973 K than the Fe-MFI zeolites due to the low coverage by *-O-2. According to our quantitative micro-kinetic analysis, this species is formed when gas-phase N2O reacts with a mono-atomic oxygen (*-O) species. This reaction pathway is strongly influenced by the degree of isolation of iron species. The higher the degree of iron isolation in the catalyst, the lower the de-N2O activity. (C) 2010 Elsevier B.V. All rights reserved.