Abstract An aluminum fluoride film covered by graphite fluoride on metallic aluminum was prepared by reaction in the ternary system of aluminum, graphite and fluorine gas at 450–550 °C. The film consisted of a large amount of aluminum fluoride covered by thin graphite fluoride layers. The contact angle of a water drop on the film was around 120°, which decreased to 85–95° during 45 d probably due to reaction with moisture and/or water drop. Almost no oxygen was detected in the film. The film formation would be based on the reduction of oxide layer on aluminum by carbon radical produced by thermal decomposition of graphite fluoride.