One aspect of the present invention relates to a catalyst system for use in olefinic polymerization, containing a solid titanium catalyst component; an organoaluminum compound having at least one aluminum-carbon bond; and an organosilicon compound comprising a (cycloalkyl)methyl group. Another aspect of the present invention relates to a method of making a catalyst for use in olefinic polymerization, involving the steps of reacting a Grignard reagent having a (cycloalkyl)methyl group with an orthosilicate to provide an organosilicon compound having a (cycloalkyl)methyl moiety; and combining the organosilicon compound with an organoaluminum compound having at least one aluminum-carbon bond and a solid titanium catalyst component to form the catalyst.