Thermoplastic vulcanizates (TPV) contain finely dispersed micron-size crosslinked rubber particles in a thermoplastic matrix. This occurs by additional breakdown of rubber induced by dynamic vulcanization during its melt-mixing with thermoplastic component. Rubber is thus turned into the dispersed inner phase. The effect of crosslinking in PP/EPDM TPV on the dynamic properties is shown at various temperatures above the melting point, strain amplitudes and frequencies. These properties also provide means for assessment of the melt morphology. Heterogeneity of the system, affecting molecular dynamics, is explored by the ESR spin probe method.