Two series of binary In2O3/MOx (M = Al, Zr, Si) catalysts with low (3 wt%) and high (10 wt%) In2O3 loadings were prepared via an incipient wetness impregnation method. The support effect has been investigated in detail by testing the propane dehydrogenation (PDH) reaction both in the presence and absence of CO2. Physico-chemical properties including surface composition, redox and acidic/basic properties of the supported In2O3 were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, H-2 temperature-programmed reduction, NH3 and CO2 temperature-programmed desorption, respectively. It was demonstrated that a higher population of the specific highly dispersed In2O3 species on support is favorable for propylene production, and the maximum propylene yield was achieved with the high-loading In2O3/Al2O3. Properties including high In2O3 dispersion and balanced acidic/basic properties, rendering synergism between dehydrogenation and reverse water gas shift, are essential for achieving high catalytic performance of PDH. (C) 2011 Elsevier B.V. All rights reserved.