The relationship between redox characteristics and catalytic activity in ethylene polymerization, with methylaluminoxane (MAO) as the cocatalyst, was evaluated for a series of homogeneous metallocenes (CP2ZrCl2, (MeCp)(2)ZrCl2, (nBuCp)(2)ZrCl2, (iBuCp)(2)ZrCl2, (tBuCp)(2)ZrCl2, CP2TiCl2, CP2HfCl2, Et(Ind)(2)ZrCl2, Et(IndH(4))(2)ZrCl2 and MeSi2(Ind)(2)ZrCl2). Catalytic activity is discussed in terms of the coordination sphere and metal center of the metallocene and compared with their electrochemical behavior in the presence of ethylene and MAO. The resulting polyethylenes were analyzed by GPC. The catalytic activity in the ethylene polymerization reaction is discussed in terms of half-life (t(1/2)) and electrochemical gap of the metallocene species. (C) 2008 Elsevier B.V. All rights reserved.