Two PP/EPDM blends with 30 wt % of EPDM and different morphologies were selectively crosslinked under a dynamic crosslinking reaction using the N,N’-m-phenylene-bismaleimide/poly(2,2,4-trimethyl-1,2,-dihydroquinoline) system. The resulting Izod impact strengths (IISs) were measured over a range of temperature. A transition point in the IIS curve, which is considered to dependent on the glass transition temperature (T-g) of the PP matrix, appeared to decrease by 5 degrees C. Scanning electron microscopy (SEM) confirmed that the crosslink reaction did not affect the blends’ morphology but did increase interfacial adhesion. Increased adhesion is considered to be a most important factor for shifting of the transition point, or apparent T-g, because it increases the free volume of the PP matrix under deformation.