Treatment of 1-beta-(4＇-acetylphenyl)vinyl-3-vinyl-1,1,3,3-tetramethyldisiloxane (I) (an AB(2) monomer) with dihydridocarbonyltris(triphenylphosphine (Ru) leads to a hyperbranched material, poly[1-beta-(4＇-acetylphenyl)vinyl-3-vinyl-1,1,3,3-tetramethyldisiloxane](II). I has been prepared by a Pd catalyzed Heck reaction between 4-bromoacetophenone and 1,3-divinyl-1,1,3,3-tetramethyldisiloxane. The structure of the soluble hyperbranched material (II) has been determined by H-1, C-13 and Si-29 NMR, as well as by IR and UV spectroscopy. It has also been characterized by GPC, TGA DSC and elemental analysis. Polymerization occurs by Ru catalyzed addition of the aromatic C-H bonds which are ortho to the activating acetyl group of I across the C-C double bond of the terminal Si-vinyl group in an anti-Markovnikov manner.