A catalyst system comprising a combination of a tin-based moisture-cure catalyst, a titanium(IV) compound that is titanium dioxide or a titanium alkoxide, and zinc oxide. A catalyst masterbatch comprising the catalyst system and a carrier resin. A moisture-curable prepolymer formulation comprising the catalyst masterbatch and a (hydrolyzable silyl group)-functional polyolefin prepolymer. Methods of making and using same. Cured polymer products made therefrom. Articles containing or made from same.