The intercalation of fluorine into graphite leads to graphite intercalation compounds (F-GICs) exhibiting potential properties such as the storage and transport of fluorine. Stage-1 compounds with C2.5F to C4F compositions are obtained by fluorination treatments at room temperature of ex-pitch, high-temperature treated carbon fibres under 10 bars F2pressure in the presence of gaseous HF. The deintercalation process of fluorine species has been studied by evolved gas analysis: the F-GICs are decomposed using the Controlled transformation Rate Thermal Analysis (CRTA) method. The thermal analysis curve obtained for stage-1 F-GICs exhibits three decomposition steps. The first two steps correspond to a simultaneous deintercalation of atomic fluorine F and gaseous HF and the third step (above 460°C) to the degradation of the compound with formation of C2F4and CF4which further dissociate in the spectrometer to CFn(1 ≤ n ≤ 3) species.