The hydrosilylation reaction of alpha,omega-bis(trimethylsiloxy)methylhydridesiloxane to phenylacetylene in the presence of catalyst-platinum hydrochloric acid (0.1M solution in tetrahydrofuran)-at 1 : 35 ratio of initial compounds, at various temperatures (40-60 degrees C) was investigated and methylsiloxane oligomers with phenethenyl substituted groups in the side chain has been obtained. It was shown that complete hydrosilylation of all active (Si-H groups do not take place. The hydrosilylation reaction order, activation energy, and rate constants were found. The synthesized oligomers were characterized by H-1 and C-13 NMR and IR spectral data. Gel-permeation chromatographic, differential scanning calorimetric, thermogravimetric, and wide-angle X-ray investigations of synthesized oligomers were carried out. (c) 2006 Wiley Periodicals, Inc.