The kinetics of propylene polymerization using a prepolymerized high-active TiCl3 catalyst with an Et(2)AlCl cocatalyst are investigated. The effect of various parameters such as Al/Ti ratio, pressure, temperature, hydrogen, and polymerization time on the rate of polymerization and yield are examined. The dependency of these parameters on the polymerization rate are studied. It is found that the variation at the rate of polymerization with the Et(2)AlCl cocatalyst concentration complies with a Langmuir-Hinshelwood type of relationship. The overall activation energy of polymerization calculated from the Arrhenius plot was found to be 11.6 kcal/mol.