Ethylene was polymerized in toluene using methylalumoxane (MAO) activated rac-(Me(2)SiOSiMe(2))[Ind]2ZrCl2 (1) and rac-(Me(2)SiOSiMe(2))[IndH(4)](2)MtCl(2) (Mt = Zr (2); Mt = Ti (3)). All three catalyst systems polymerize ethylene with high activity. The molecular weight of polymer produced with zirconocene (1) was up to a weight-average molecular weight <(M)over bar (w)> = 1.1 x 10(6) at low polymerization temperature (<20 degrees C) under atmospheric pressure. The titanocene catalyst 3 shows lower activity and produced lower molecular weight polyethylene than zirconocenes 1 and 2. Replacement of aromatic rings in 1 by cyclohexane rings, leading to 2, increases activity and reduces molecular weight. The catalyst systems show a dependency of the activity on temperature.