The norbornene/ethylene copolymerization was investigated using Me2SiCp2MCl2 (M = Zr, Ti)/EBAO and MAO as catalyst systems (EBAO: mixed ethyl-isobutylaluminoxane, MAO: methylaluminoxane). The copolymers were characterized by DSC and C-13 NMR. Copolymers with high content of norbornene and high Tg were obtained with the mixed EBAO. It is suggested that the copolymerization is greatly influenced by the state of the ion pair of the metallocene catalyst. The effect of aluminoxane on the composition and the microstructure of copolymer is discussed.