New siloxanes with acid-sensitive substituents have been synthesized by means of hydrosilylation, starting from methylhydrosiloxanes. Details of the preparation and characterization are reported. p-t-Butoxycarbonyloxystyrene, p-t-butoxystyrene and t-butyl methacrylate turned out to be excellent reagents in these experiments. H-1, C-13 and Si-29 nuclear magnetic resonance techniques were used for characterization. The ratio between alpha and beta addition appears to be strongly dependent on the substituents at the vinyl group of the organic moieties.