Supported catalyst systems and methods of forming the same are described herein. In one specific embodiment, the methods generally include providing an inorganic support material and contacting the inorganic support material with an aluminum fluoride compound represented by the formula AlFpX3-pBq to form an aluminum fluoride impregnated support, wherein X is selected from Cl, Br and OH−, B is H2O, p is selected from 1 to 3 and q is selected from 0 to 6. The method further includes contacting the aluminum fluoride impregnated support with a transition metal compound to form a supported catalyst system, wherein the transition metal compound is represented by the formula [L]mM[A]n; wherein L is a bulky ligand, A is a leaving group, M is a transition metal and m and n are such that a total ligand valency corresponds to the transition metal valency.