A simple Lewis acid, boron trifluoride etherate, was applied as novel activator towards a new nickel precursor Ni(PPh3)(4) for the polymerization of norbornene. The system Ni(PPh3)(4)/BF3OEt2 is highly active in the polymerization of norbomene. The product obtained showed exclusively 2,3-connectivity of polymer backbone. Catalyst activities up to 4200 kg/(mol Ni h) and intrinsic viscosities up to 1.30 dl/g were observed at appropriate conditions. The catalytic activity of the system is comparable to that of the most active nickel systems with traditional MAO activators. Catalyst activity and polymer molecular weight can be controlled by variation of the reaction parameters over a wide range. Polymer characterization was carried out by IR, H-1 and C-13 NMR, TGA, DSC, and viscosimetry. Nickel hydrides are likely to be catalytically active species. (C) 2003 Elsevier B.V. All rights reserved.