Pd(II) catalysts with nitrilo ligands and BF4- counter ions give the best results in vinylic polymerization of norbornene. Absolute molecular weight determination of polynorbornene (PN) by means of light scattering and the three-dimensional shape of PN were also investigated. By correlation of molecular weights (M) over bar(W) with intrinsic viscosity (Staudinger-index) [eta], yield a close to 0.5 exponent for the Mark-Houwink equation with sol vents chlorobenzene and cyclohexane at 25 degrees C expected for polymer molecules with confined conformation. The vinylic polymerization of norbornene with [(CH3CN)(4)Pd][BF4](2) (I) in nitromethane in the presence of ethylene results in PN with narrow molecular weight distribution. No termination and transfer reactions were found, nor any incorporation of ethylene could be detected.