Utilization of Fe-Beta for NH3-SCR of NOx in diesel engine applications is severely limited by hydrocarbon poisoning. In this work, a series of hybrid catalysts are prepared by mechanical mixing of zeolites and oxides, and their activity for the selective catalytic reduction of NOx with NH3 is investigated in the presence of propene. Results have shown that a catalyst prepared by mixing Fe-Beta and MnOx/CeO2 in a mass ratio of 1:1 exhibits high SCR activity. NOx conversion in the temperature range 200-400 degrees C has exceeded 90% at a GHSV of 80,000 h(-1), with low selectivity to N2O. By the combined DRIFTS and MS measurements, the function of MnOx/CeO2 in the hybrid catalysts is discussed. This hybrid catalyst is able to convert C3H6 to intermediates containing C=O and COO functionalities, thereby decreasing carbon deposition on the zeolite and reduce the competitive adsorption between C3H6 and NOx. Moreover, these intermediates react with NOx at lower temperatures than do the carbonaceous deposits on Fe-Beta, enhancing the NOx reduction activity.