Various blends of polypropylene and ethylene propylene diene terpolymer were prepared. In these blends, rubber phases were compounded with an optimum sulfur curing system. The equivalent cure time and state of cure of the mixes were studied in the temperature range from 120 to 190 degrees C by a rheometer. The temperature-independent parameters (E-1, E-2, S-1, and S-2) and specification of the temperature dependence curing rate constant (k) and induction period (t(0)) were determined. The activation energies of the crosslinking reaction are almost similar for the virgin EPDM and EPDM/PP mixes. The value 9 Kcal/mol was considered sufficiently accurate for these mixes. A discussion of temperature-conversion factor of the mixes is also provided.