], were applied as media of the Cp 2 TiCl 2 catalyst for biphasic ethylene polymerization. The studied aralkyl ionic liquids ensure greater stability of the catalyst at higher temperatures and more regular morphology of the produced polyethylene than analogous 1-n-alkyl-3-methylimidazolium chloroaluminates. The alkylaluminium compound participates in the termination reaction of the polymer chain. The catalyst is stable and enables recycling of the ionic liquid phase in the consecutive polymerization reactions. The [Ph-C 2 mim][AlCl 4 ] ionic liquid and AlEt 2 Cl alkylaluminium compound turned out to be the most suitable for the biphasic process. The influence of the kind of ionic liquid, alkylaluminium compound (AlEt 2 Cl and AlEtCl 2 ), activator/catalyst molar ratio, reaction temperature, reaction time and catalyst recycling on the polymerization performance as well as polyethylene properties such as molecular weight (M w ), polydispersity, melting temperature, crystallinity degree, bulk density and particle size is presented.