A supported polyolefin catalyst activator, comprising a four coordinate anion having a direct chemical bond to a catalyst carrier, wherein said anion is comprised of a neutral, three coordinate compound, MR.sub.3, and a carrier having oxygen containing functionalities, wherein M is selected from the group comprising boron, tellurium, aluminum, gallium, indium and mixtures thereof, and R's can be the same or different and are selected from the group comprising alkyls, alkoxys, alkenyls, halogen substituted alkyls, alkoxys, and alkenyls, aryls, aryl halides, halides and mixtures thereof; and a cation counter ion to said anion, wherein said cation is a protonated base or a Lewis Acid capable of protonating or abstracting a moiety, such as an alkyl or aryl, from a transition metal containing catalyst precursor resulting in a cationic transition metal species.