The effect of ultrasounds on the platinum-catalyzed hydrogenation of cinnamaldehyde was studied in the liquid phase over Pt/SiO2, Pt/Al2O3, Pt/C and EuroPt-1 catalysts under mild experimental conditions (333 K, 1 atm H-2). The sonochemical pretreatment was found to be highly beneficial for the selective formation of cinnamyl alcohol (up to 80%) over silica-supported catalysts, besides the significant reaction rate increase (two-fold increase). The actual changes of the catalysts were studied by transmission electron microscopy, and the mechanistic interpretation of the sonochemical effect is also given.