BaO and SO42- modified Pt/Al2O3 catalysts were prepared by a two-step wetness incipient method. The textural properties were characterized by BET, XRD, ex situ FTIR. Propene oxidation activity under various redox ratio (S=[O-2]/4.5[C3H6]) was evaluated. The oxidation process and intermediate species were studied by detailed in situ FTIR experiments including propene adsorption CO IR and propene TPO. It is observed that the addition of BaO promotes the catalytic oxidation of propene over Pt/Al2O3, while sulfation results in the deactivation of Pt/Al2O3. The good activity of Pt/BaO/Al2O3 is ascribed to the weakened propene adsorption, the formation of reactive enolic species and easy oxidation of intermediate CO by active oxygen at Pt-Ba interface. On the contrary, the strong adsorption of propene as well as the intermediate CO poisoning are proved to be the main reasons for the deactivation of Pt/SO42-/Al2O3. A general reaction scheme is proposed based on these results. (C) 2013 Elsevier B.V. All rights reserved.