The new nanocomposite thermoelastoplasts on the basis of isotactic polypropylene (PP) and ethylene-propylene diene rubber (EPDR) with application of nanofiller – nickel nanoparticles stabilized on polymer matrix have been prepared. The influence of nickel nanoparticles on properties of the prepared nanocomposites by the methods of X-ray phase (RPhA) and thermogravimetric (TGA) analyses has been investigated. It has been shown that an introduction of nanoparticles in PP/EPDR leads to the improvement of the rheological properties and increase of thermal stability of nanocomposites in keeping of their strength indices.