Kinetics of the reactions of allylsilanes (1) and silyl enol ethers (2) with benzhydrylium ions (3) were studied by UV−vis spectroscopy in dichloromethane at 20 °C. The less than three times higher reaction rates of the tris(trimethylsilyl)silyl compounds in comparison to the corresponding trimethylsilyl compounds indicate that the previously reported strong electron-donating effect of the supersilyl group operates only in the α-position and not in the β-position.