Homo- and copolymerization of ethylene and norbornene were investigated with bis(beta-diketiminato) titanium complexes [ArNC(CR3)CHC(CR3))NAr](2)TiCl2 (R = F, Ar = 2,6-diisopropylphenyl 2a; R = F, Ar = 2,6-dimethylphenyl 2b; R = H, Ar = 2,6-diisopropylphenyl 2c; R = H, Ar = 2,6-dimethylphenyl 2d) in the presence of methylaluminoxane (MAO). The influence of steric and electric effects of complexes on catalytic activity was evaluated. With MAO as cocatalyst, complexes 2a-d are moderately active catalysts for ethylene polymerization producing high-molecular weight polyethylenes bearing linear structures, but low active catalysts for norbornene polymerization. Moreover, 2a-d are also active ethylene-norbornene (E-N) copolymerization catalysts. The incorporation of norbornene in the E-N copolymer could be controlled by varying the charged norbornene. C-13 NMR analyses showed the microstructures of the E-N copolymers were predominantly alternated and isolated norbornene units in copolymer, dyad, and triad sequences of norbornene were detected in the E-N copolymers with high incorporated content of norbornene. (c) 2007 Wiley Periodicals, Inc.