Hydrosilylation of a,o-bis(trimethylsiloxy)-methylhydrosiloxane to alkenes in the presence of a catalyst was performed at several temperatures (30-708C). Combtype methylsiloxane oligomers with various alkyl substituted groups in the side chains have been obtained. Not all active BSiÀ ÀH groups participate in the reaction. The reaction order, activation energies, and rate constants have been determined. The synthesized oligomers were characterized by 1 H, 13 C, 1 H COSY NMR, and FTIR spectroscopy. Calculations using the quantum-chemical semiempirical AM1 method for modeling reaction between methyldimethoxysilane [Me(MeO) 2 SiH] and hexene-1 were performed to evaluate possible reaction paths. For all initial, intermediate, and final products, enthalpies of formation as a function of the distance between BCÀ ÀSiB bonds are calculated. The hydride addition is energetically more favorable according to the antiMarkovnikov rule than according to the Markovnikov rule. Comb-type oligomers were characterized by gel-permeation chromatography, differential scanning calorimetry, thermogravimetry, and wide-angle X-ray diffractometry.