The kinetics of N2O decomposition over a commercial iron zeolite catalyst was determined in an integral laboratory reactor. The formal kinetic equation developed permits a very good description of the observed rate as a function of temperature and the concentrations of N2O, NO and H2O. The influence of mass transfer phenomena on the reaction rate was investigated experimentally by using different catalyst particle sizes. A reactor model taking into account internal and external mass transfer resistances, axial dispersion and pressure drop was developed. Reactor simulations for different configurations revealed that random packings of catalyst extrudates must be placed in radial-flow reactors to limit the pressure drop. Honeycomb monolith catalysts are attractive alternative geometries because they allow both better utilization of active material and the design of more compact reactors.