A study was conducted to demonstrate the use of the Mitsunobu reaction as an efficient tool for the post-functionalization of fullerene mono- and hexakis-adducts. A C60 mono-adduct bearing 2 hydroxyl groups and a hexakis-adduct with 12 hydroxyl functions was prepared to conduct the investigations. Ethylene glycol was mono-protected as tert-butyldimethylsilyl ether and diesterification of malonic acid was performed in the presence of DCC in 97% yield. Hexakis-adduct was synthesized using the optimized conditions. The resulting crude mixture was purified on silica-gel column to afford an inseparable mixture of pentakis- and hexakis-adduct. The mixture of both isomers were subjected to desilylation using an excess of hydrogen chloride as a methanolic solution.