The boron trifluoride etherate, BF3OEt2, was used as an activator towards bis(acetylacetonate)palladium precursor in the polymerization of norbornene. The catalyst system Pd(Acac)(2)/BF3OEt2 was highly active in the polymerization of norbornene. Catalytic activity up to 20,220 kg/(mol Pd (.) h) and intrinsic viscosities up to 2.64 dL/g were observed, respectively. Catalytic activity, polymer yield and polymer molecular weight could be controlled by varying the reaction parameters. The molar mass distribution indicates a single-site, highly homogeneous character of the active catalyst species. NMR spectroscopy study of the polymer showed exclusively 2,7-enchained repeating units of polymer backbone. (C) 2003 Elsevier B.V. All rights reserved.