Abstract: The present invention provides a composition and a process wherein a metallocene catalyst is dissolved in an alumoxane which has been dissolved in a solvent to form a concentrated stock solution of metallocene-alumoxane which can be stored for at least 14 days. The metallocene-alumoxane solution is stored under an oxygen- and water-free environment and more preferably under argon at temperatures that can range from about 25 degrees Fahrenheit (-4 degrees C.) to about 85 degrees Fahrenheit (29 degrees C.). Before or at the time that the metallocene-alumoxane solution is injected into the reactor, it is diluted with a second solution comprised of either an alumoxane, an aluminum alkyl or mixtures thereof dissolved in an oleaginous solvent. The addition of the aluminum based co-catalyst serves a two fold purpose.