A new method is reported which enables us to effectively poison strong acid sites on multicomponent metal oxide catalysts, responsible for undesired total oxidation reactions, by chemical vapor phase deposition of silane and subsequent oxidation, In the partial oxidation of propane over VSb2WOx/Al2O3 the selectivity of the primary product propene could be enhanced by 10% using a SiOx modified catalyst compared to the unmodified sample, The selectivity towards the consecutive product acrolein also increased by a factor of 3; however, it remained low, never exceeding 6%, The effect of poisioning is explained on the basis of the changes in the physico-chemical bulk and surface properties due to the surface silane/N2O modification and treatment under reaction conditions.