A method for the preparation of well-defined crystallites of MgCl2-supported Ziegler-Natta catalysts on Si wafers has been developed. This has been achieved by the spin-coating of a MgCl2 solution onto a flat Si wafer, followed by controlled crystal growth to give well-defined MgCl2 . nEtOH crystallites. The growth of the crystallites on the flat silica facilitates their characterization using electron and scanning probe microscopy. The relative proportions of 120 degrees and 90 degrees edge angles indicate the preference for the formation of a particular crystallite face for the MgCl2. Polyethylene has been identified to be formed on the lateral faces of the crystallite.