X-ray phase analysis (XRPA), differential thermal analysis (DTA), and IR spectroscopy studies were performed to investigate stepwise transitions of the fluorographite intercalation inclusion compound (host) with acetonitrile (guest). When heated in a guest atmosphere to 260(±8)°C, the compound of the first stage of saturation with a spacing of I c = 9.47 Å undergoes sequential disproportionation into gaseous acetonitrile, a compound of the second stage (I c = 15.52 Å), a compound of the fourth stage of occupation (I c = 27.77 Å), and solid solutions based on the fluorographite matrix (I c = 6.05 Å) that form “residual compounds.” In air the “residual compound” of graphite fluoride is formed at lower temperatures. Conditions of mutual transitions and formation of metastable states have been determined for which the domain model with coexisting microphases of different stages of occupation is discussed.