The 1-(2,6-dibenzhydryl-4-nitrophenylimino)-2-mesityliminoacenaphthylnickel bromide (1) is supported on the silica modified by adding different aluminum compounds. The immobilized catalysts show high activities toward ethylene polymerization being initiated by the co-catalyst either i Bu 3 Al or Et 2 AlCl. The resultant polyethylenes display moderate branching (30–50 CH 3 /1000C) along with high molecular-weights (up to 1.5 × 10 6 g mol −1 ) as well as narrow molecular weight distributions (2.1–2.4). The kinetic study of immobilized catalysts has been conducted and compared with that of homogeneous 1/Et 2 AlCl system. The supported nickel catalysts produce spherical particles of branched PEs at slurry polymerization without reactor fouling and could be practically attractive.