Toughening of homopolymer polypropylene (PPH) in the post reactor step by incorporating external elastomers has become an attractive area of research. In this investigative work, PPH was post-reactor blended with different types of Polyolefin elastomers (POE) that were selected based on the co-monomer type and density. The influence of three different level (10, 15, and 20 wt. %.) ofPOE on the mechanical, thermal, and morphology properties were investigated. The performance behavior of PPH/POE blends with and without a nucleating agent was compared to in situ (in the reactor) modified PPH with Ethylene Propylene Rubber (EPR) known as Impact Copolymers Polypropylene (ICP) or heterophasic polypropylene. The addition of POE in PPH was shown to improve the toughness of the blends at room temperature while the stiffness and tensile strength decreased. The addition of a nucleating agent was noted to improve the toughness and stiffness of the above mentioned blends compared to their non-nucleated counterparts, while the tensile strength remained unchanged. The in-situ modified impact polypropylene (ICP) has shown better mechanical properties than PPH/POE blends at the same level of rubber content of 15 wt. %. On other hand, the nucleated ICP has presented similar impact performance at room temperature compared to the nucleated blend PPH/POE with 15% POE based on C4 co-monomer. At -20 °C, the impact strength results showed no significant improvement in PPH/POE blends with and without addition of the nucleating agent and this could be due to the ductile-brittle transition does not taking place at this temperature while, ICP shown better toughness at this temperature. The morphology of PPH/POE blends was investigated by Scanning Electron Microscopy (SEM). The SEM micrographs have shown clearly the phase separation of the blends components thus demonstrating the immiscibility of the blend system. The addition of the nucleating agent was seen to decrease the domain size of POE phase thus leading to the improvement in the toughness properties of the blends. On the other hand, ICP materials have shown more uniform dispersion of the elastomer phase than the PPH/POE blends. Th