Multi-component blends of polypropylene (PP), ethylene-1-octene copolymer (EOC) and zinc oxide (ZnO) are prepared by melt mixing using two-roll mill. Samples prepared by compression moulding have been investigated by using differential scanning calorimeter (DSC). It is found that addition of ZnO particles decreases PP melting point and increases crystallinity degree of PP. ZnO works as nucleation agent for PP by increasing quantity of crystallization centers, but at the same time decreasing structure quality. Because of the structure change mechanical properties are affected. At lower nanoparticle concentration some reinforcement effect I observed, while at higher particles concentration brittlening occurs. Crystalline structure and particles nature increases thermal stability of PP and PP/EOC blends.