The structure development, rheological behavior, viscoelastic and mechanical properties of dynamically cured blend based on the ethylene-propylene-diene terpolymer (EPDM) and polypropylene (PP) with a ratio of 60/40 by weight were studied. The variation of two-phase morphology was observed and compared as the level of curing agent was increased. Meanwhile, as the level of curing agent increased, viscosity as a function of shear stress always increased at a shear stress range of 2.2 X 10(4) to 3.4 x 10(5) Pa at the temperature of 200degreesC, yet viscosity of the blend approached each other at high shear stress. Dynamic mechanical spectra at different temperatures show that dynamic modulus (E') of the blend exhibits two drastic transitions corresponding to glass transition temperature (T-g) of EPDM and T-g of PP respectively. In the blends T(g)s of EPDM increase and T(g)s of PP almost remain unchangeable with an increase in curing agent level. Tensile strength increased, yet elongation at break decreased as the level of curing agent is increased. (C) 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 357-362,2004.