New supported catalysts on the basis of cyclopentadienylindenylzirconium dichloride (CpIndZrCl(2)) anchored on silica with a trisiloxane spacer (ZATS) and a pentamethylene spacer (ZAPM) were prepared and used for ethylene polymerization with modified methylaluminoxane (MAO) as cocatalyst. ZATS and ZAPM produce polyethylene with lower molecular weight but show higher activity than silica-supported CpIndZrCl(2) which was prepared by reacting zirconocene directly with silica, i.e., the activity of silica-supported CpIndZrCl(2) is enhanced by introducing a spacer between silica surface and metallocene species.