Cobalt (Co), with its low resistivity, excellent resistance to electro-migration with co-deposition property, and void-free seamless fill ability, is likely to transform the landscape of integrated circuits in many areas, especially in logic contacts and interconnects. Chemical mechanical polishing has been recognized as the exclusive manufacturing approach to achieve global and local planarization of wafer surfaces. In this work, we proposed an innovative hydrogen peroxide polishing slurry, applying phthalic acid as the complexing agent and oleic acid as the corrosion inhibitor at a pH of 10. From the results of appropriate material removal/static etching rates as well as the smooth surface morphologies, phthalic acid and oleic acid are shown to be qualified in HP-based slurries for heterogeneous materials of Co interconnects. It can be concluded that with the addition of complexing agent phthalic acid in HP-based slurries, the transformation of oxidization of low-valence compounds was partially replaced by stronger complexing action, making the removal mechanism be attributed to the combined oxidization and complexation. When oleic acid is introduced, it could react with Co oxides to form a polymer protection layer adsorbing on Co films, achieving an inhibition effect to avoid Co excessive corrosion.