This invention provides a process for producing a catalyst composition comprising contacting at least one group 4 metallocene, at least one organoaluminum compound, and at least one solid. The solid is selected from the group consisting of titanium tetrafluoride, zirconium tetrafluoride, and a treated solid oxide compound. The treated solid oxide compound comprises a solid oxide compound having titanium tetrafluoride or zirconium tetrafluoride deposited on the surface of the solid oxide compound. The solid oxide compound comprises oxygen and at least one element selected from the group consisting of groups 2-9 and 11-17 of the Periodic Table of Elements, including lanthanides and actinides. This invention also provides the catalyst composition produced by this process.