The simultaneous catalytic reduction of both NOx and N2O in excess O-2 using propene as the reductant was studied in the absence and in the presence of 10% H2O and 50 ppm SO2. Reduction took place in a dual-bed catalytic reactor consisting of In/Al2O3 in the upper layer and of Ru/Al2O3 in the lower one. The effect of SO2 and/or H2O on the NOx and N2O reduction was examined. Transient experiments showed that in the presence of SO2 in the feed the active sites were poisoned, the N2O conversion dropped to zero, and the NOx reduction was significantly reduced. We were motivated by this deactivation to apply a reaction/regeneration scheme for the continuous NOx and N2O reduction in the presence of SO2 and H2O. Two reactors loaded with the same catalytic samples were connected in parallel. One was fed with the reactive gas mixture, while at the same time, the other was regenerated with H-2. The periodic regeneration of the dual-bed catalytic reactor resulted in the simultaneous reduction of NOx and N2O even when the feed contained SO2 and H2O.