A two component catalyst activator comprises: 1) a Lewis acidic organoboron (or an orgonoaluminum) component; and 2) a component defined by the formula AOSO2R wherein A is a pseudo cationic group and R is a hydrocarbyl or substituted hydrocarbyl. The catalyst activator is used in combination with a transition metal catalyst for the polymerization of olefins. The catalyst activator provides improved catalyst activities. It is especially useful in solution polymerizations because of desirable solubility characteristics in comparison to the borate salts used in prior activators.