Functionalized metallocene precursors (BrMe2SiC5H4)CpZrBr2 (1), (BrMe2SiC5H4)(2)ZrBr2, (2) (Br2MeSiC5H4)(2)ZrBr2 (3), and [1,3-(BrMe2Si)(2)C5H3](2)ZrBr2 (4) were immobilized on partially dehydroxylated silica (PDS) and screened for ethylene polymerization in slurry reactions conducted in toluene using methylalumoxane (MAO) as the cocatalyst. The effects of metallocene precursor structure, catalyst immobilization method, and catalyst loading are presented in terms of catalytic activity, polymer molecular weight distribution, and stability of the catalysts toward leaching. (C) 2003 Elsevier B.V. All rights reserved.