The synthesis of polysiloxanes with pendant unsaturated cyclic fragments have been successfully performed by hydrosilylation reactions of polymethylhydrosiloxane with 4-vinyl-1-cyclohexene in the presence of platinum hydrochloric acid (0.1 M solution in THF), Karstedt's catalyst (Pt-2[(VinSiMe(2))(2)O](3)) and platinum on the charcoal (5%). Reactions were carried out at various temperatures with different ratios of initial compounds. It was shown, that not all active Si-H groups take part in the hydrosilylation reaction. Some kinetic parameters of reactions were studied. The synthesized oligomers were characterized by FTIR, H-1, C-13, H,H-COSY, and C,H-correlation NMR spectroscopy. Calculations using the quantum-chemical semi empirical AMI method for modeling reactions between methyldimethoxysilane [Me(MeO)(2)SiH] and 4-vinyl-1-cyclohexene were performed to evaluate possible reaction paths. Synthesized oligomers were characterized by gel-permeation chromatography, differential scanning calorimetric, thermogravimetric, and wide-angle X-ray analyses. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 114: 892-900, 2009