Use of hexafluoropropylene oxide (HFPO) as a comonomer appreciably enhances physical and chemical properties of fluoropolymers. It is also essential to the preparation of fluorinated polyethers which are the major materials for manufacturing fluorinated ion-exchange membranes such as Nafion and Flemion. HFPO was successfully obtained from a liquid-phase epoxidation of hexafluoro propylene (HFP), which occurred in the surface interface between an aqueous hypochlorite and an organic solvent, 1,1,2-trichloro-1,2,2-trifluoroethane (F-113), containing HFP. Yield and production rate of HFPO increased along with the initial concentration of NaOCl. The yield of HFPO also changed with the ratio of NaOCl to F-113 and with types and concentrations of sulfactant.