The role of Ag in simultaneously catalyzing NO reduction and C3H6 oxidation was shown to be strongly dependent on the redox properties of its local environment. Under an atmosphere of 1,000 ppm NO, 3,000 ppm C3H6, and 1% O-2 and a GHSV of 30,000 h(-1), a perovskite La0.88Ag0.12FeO3 prepared by reactive grinding is active giving a complete NO conversion and 92% C3H6 conversion at 500 degrees C. These values are much higher than the NO conversion of 55% and C3H6 conversion of 45% obtained over a 3 wt.% Ag/Al2O3 catalyst under the same conditions. Under an excess of oxygen (10% O-2) a good SCR performance with a plateau of N-2 yield above 97% over a wide temperature window of 350-500 degrees C along with C3H6 conversion of 90% at 500 degrees C was observed over Ag/Al2O3, while minor N-2 yields (similar to 10% at 250-350 degrees C) and high C3H6 conversions (reaching similar to 100% at 450 degrees C) were obtained over La0.88Ag0.12FeO3. Abundant molecular oxygen is desorbed from Ag substituted perovskite after 10% O-2 adsorption as verified by O-2-temperature programmed desorption (TPD). This reflects the strongly oxidative properties of La0.88Ag0.12FeO3, which lead to a satisfactory NO reduction at 1% O-2 due to the ease of nitrate formation but to a significant C3H6 combustion above that value. The formation of nitrate species over the less oxidizing Ag/Al2O3 was accelerated under an excess of oxygen resulting in an excellent lean NO reduction behavior. The redox properties of silver catalysts could be adjusted via mixing perovskite with alumina for an optimal elimination of both NO and C3H6 over the whole range of oxygen concentration between 0 to 10%.