Blends of isotactic polypropylene (iPP) and hydrogenated oligo(cyclopentadiene) (HOCP) containing 30% or less HOCP have been studied by small-angle X-ray scattering in the temperature range 25 to 160 degrees C. The structure of blends has been analysed in terms of a pseudo two-phase model consisting of stacks of lamellae whose thickness is a function of temperature and composition. Structural parameters of the model have been derived and their temperature and composition dependences have been interpreted in the light of existing theories.