A series of Sc2O3-modified (1-5%) In2O3/Beta composites were prepared by the deposition-precipitation method. These catalysts were characterized by X-ray diffraction, N-2 adsorption, temperature-programmed desorption of NH3 and CO2, temperature-programmed reduction, X-ray photoelectron spectroscopy and Al-27 magic-angle spinning nuclear magnetic resonance. The incorporation of Sc2O3 into In2O3/Beta results in enhanced catalyst stability for the conversion of ethanol to propylene, which is due to inhibition of the reduction of In3+ to In-0 upon Sc2O3 modification.