Silica-supported Sn-Pt catalysts, prepared by controlled surface reactions between hydrogen adsorbed on platinum and tin tetraethyl, showed high activity and selectivity in the gas phase hydrogenation of crotonaldehyde to crotyl alcohol. The selectivity of the formation of crotyl alcohol (S-CO) had a strong dependence of the Sn/Pt ratio. The highest S-CO selectivity (around 70%) was obtained at Sn/Pt = 3. The characteristic feature of the Sn-Pt/SiO2 catalyst in the given reaction is the development of the S-CO selectivity during the time-on-stream period. The observed phenomenon was described as a reactant induced catalyst activation.