Bis(phenoxy-ether) Ti complexes were investigated as ethylene polymerization catalysts. The complexes, combined with iBu(3)Al/Ph3CB(C6F5)(4) or methylaluminoxane (MAO) cocatalysts, can be highly active single site catalysts, which display activities (turnover frequency, max. 2065 min(-1)) comparable with that of a highly active bis(phenoxy-imine) Ti complex/MAO system and provide very high molecular weight polyethylenes (M-v 2040 000 5 420 000) at 25degreesC under atmospheric pressure.