The polymerization of bis(4-ethynylphenyl)methylsilane catalyzed by RhI(PPh3)(3) afforded a regio- and stereoregular hyperbranched polymer, hb-poly[(methylsilylene)bis(1,4-phenylene-trans-vinylene)] (poly(1)), containing 95% trans-vinylene moieties. The weight loss of this polymer at 900degreesC in N-2 was 9%. Poly(1) displayed an absorption due to the pi-pi* transition around 275 nm as a shoulder and a weak absorption around 330 nm due to pi-to-sigma charge transfer, which was finally seen in the corresponding linear polymer.