The interfacial tension (IFT) of Polypropylene/Polyamide6 (PP/PA6) and Polypropylene/Polyethylene terephthalate (PP/PET) pairs was evaluated as a function of temperature and Glycidyl Methacrylate grafted PP (PP-g-GMA) content, using the pendant drop method (PDM). PP-g-GMA was used as the compatibilizer in both systems. It was observed that IFT values of both systems showed a linear decrease with increasing temperature. Also, presence of a small amount of PP-g-GMA compatibilizer in the PP phase reduced the IFT of polymeric pairs dramatically, while adding more, compatibilizer had no influence on IFT due to the saturation of the interface. The saturation concentrations of GMA in the PP phase were obtained for 0.05 wt. % and 0.025 wt. % in PP/PA6 and PP/PET systems, respectively. The IFT values of compatibilized systems were reduced by 68% for PP/PA6 and 57% for PP/PET pairs compared to non-compatibilized ones.