THE MECHANICAL, dynamic thermal mechanical, thermal, and morphological properties of pre-irradiated isotactic polypropylene (iPP) and pre-irradiated hydrogenated oligocyclopentadiene (HOCP) blends were studied. Melting points (Tm), heat of fusion (Hf) and overall crystallinity of iPP/ HOCP blends decreased as a result of addition of pre-irradiated HOCP resin. Incorporation of HOCP resin in iPP matrix exhibited better mechanical properties, (tensile stress and elongation at break) as compared with blank iPP sample. The dynamic thermal mechanical data showed that the addition of HOCP resin slightly decreased the storage modulus from -100 oC up to 0.0 oC and then after there is an abrupt change was observed. Also, the modulus loss curves illustrated the presence of a single peak indicating a good dispersity of compatible systems. Morphological analysis of iPP/ HOCP blends investigated the presence of a homogenous phase in the amorphous regions of the polymeric system. Modification of iPP matrix in the presence of HOCP resin with different molecular wt should be allow a distortion of the crystalline structure and therefore the HOCP resin will be partially dissolved (compatible) in the amorphous phase and partially trapped in iPP crystal phase.