The vinyl polymerization of norbornene with di-mu-chloro-bis-(6-methoxybicyclo[2.2.1]hept-2-ene-5sigma,2pi)-palladium(II), Ni(acetylacetonate)(2) and Ni(2-ethylhexanoate)(2) in combination with methylalumoxane (MAO) was investigated by varying the molar MAO:metal-complex ratio, the norbornene: metal ratio and the metal concentration. The effects on the catalyst activity could be explained with a complexation equilibrium for the active homogeneous complex. Activity data in combination with polymer analyses suggest that at low, yet economical AI(MAO):metal ratios of 100 the fraction of active metal centers is less than 15%. The turnover frequency for the monomer insertion was found to reach 50 s(-1). Polydispersities around M-w/M-n = 2 indicate a coordination polymerization with chain transfer and a single-site character of the active centers.