Silica and Merrifield resin were used as carriers for the support of alpha-diimine nickel(II) precatalysts for ethylene polymerization. The alpha-diimine ligands containing allyl were modified by introducing the reactive Si-Cl end-group, allowing their immobilization via a direct reaction of the Si-Cl groups with the silanols on silica surface or the hydroxyls on the ethanolamine-modified Merrifield resin. The resulting supported alpha-diimine ligands were characterized by analytical and spectroscopic techniques (NMR and Fr-IR). The complexation reactions of the Supported ligands with NiBr2(dimethylether) (DME) gave rise to supported alpha-diimine nickel(II) precatalysts. These heterogeneous precatalysts exhibited high activity for ethylene polymerization in the presence of modified methylaluminoxane (MMAO) as a cocatalyst. The molecular weights of the polyethylenes obtained with the supported precatalysts were much higher than those produced with the corresponding homogeneous precatalysts. (c) 2008 Elsevier B.V. All rights reserved.