We have investigated a novel approach wherein we undertake surface fluorination of nanometer sized Fe3O4 conversion compound into corresponding oxyfluoride with the goal toward enhancing their energy density as well electrochemical performance stability. This is achieved by using direct fluorination of nano-Fe3O4 in a fluidized bed reactor under controlled reaction atmosphere and temperature. X-ray photoemission spectroscopy analysis shows conclusive evidence of the surface fluorination of Fe3O4 particles at a reaction temperature of 100 C and higher forming a surface oxyfluoride phase that can be nominally described as FeOF. Formation of oxyfluoride phase is confirmed by the appearance of a higher potential intercalation plateau during the electrochemical charge-discharge cycling. Based on the experimental results, various pathways are discussed for the formation of oxyfluoride species on the surface. © 2013 American Chemical Society.