gamma-Al2O3 is widely present as a support in catalytic application. However, the transformation of gamma-Al2O3 into the undesired hydrated boehmite (y-AlOOH) under the aqueous reaction conditions usually results in an irreversible inactivation of supported Al2O3 catalysts. Toward suppressing the hydration of gamma-Al2O3 in the process of catalytic reactions, herein we have devised a new strategy by exploring the SiH4 treatment for successful preparation of Si-Pd/Al2O3 catalysts. SiH4 treatment enables a significant improvement in the poor stability of Pd/Al2O3 for selective oxidation of toluene because SiH4 could effectively anchor palladium nanoparticles and inhibit the formation of boehmite by reacting with unsaturated aluminum sites to reduce the intensity of Lewis acid sites on the surface of gamma-Al2O3. Pd/Al2O3 pretreated with SiH4, that is Si-Pd/Al2O3, provides high catalytic activity and stability in the aqueous oxidation of toluene even at high temperature. Moreover, Si-Pd/Al2O3 is reusable without obvious loss of the catalytic activity and selectivity, compared to Pd/Al2O3.