Solid polymethylaluminoxane (sMAO) supported ansa-bridged permethylindenyl zirconocenes me(2)B(Cp-R ,I*)ZrX2 ({(eta(5)-C9Me6)Me2Si(eta(5)-C5H3R)}ZrX2; R = H, Me, and Bu-n; X = CI, Br, Me, and CH 2 Ph) have been investigated as catalysts for the slurry-phase polymerization of ethylene in the presence of H-2. The catalysts demonstrated remarkable stability to H-2 both in a high-throughput screening system and in a 2 L batch reactor, with an almost constant ethylene uptake maintained throughout the polymerization runs. The catalysts demonstrated very high ethylene polymerization activities, almost 3 times higher than sMAO-(Cp-nBu)(2)ZrCl2 (industrial standard zirconocene catalyst) under the same conditions. The presence of small quantities of H-2 (<1%) led to significant decreases in polymer molecular weights to produce commercially desirable polyethylene waxes (M-n < 10 kg mol(-1)) in a batch reactor.