[en] The thermal expansion of the interlayer spacing and the intensity ratio I(004)/I(002) of the diffraction lines of graphite-bromine residue compounds were measured between room temperature and 700⁰C using a high temperature X-ray diffractometer. At about 330⁰C, both the c-spacing and the intensity ratio of diffraction lines were found to show a break, i.e. the c-spacing of the residue compound which shows normal linear expansion below 330⁰C, has a considerably smaller thermal expansion coefficient between 330 and 500⁰C. Over this temperature, it becomes nearly equal to that of original graphite. On cooling, the anomaly in the reverse direction occurs between 330 and 200⁰C. The intensity ratio of the diffraction lines of the residue compounds is smaller below 330⁰C as compared with that of original graphite, but above 500⁰C, they are almost the same. The thermal diffusivity and the heat-capacity studies were also performed in the same temperature range. The thermal diffusivity curve shows a break, and the heat-capacity curve has a small hump around 330⁰C. At temperatures higher than 330⁰C, both of these properties agree with those of original graphite. The structure of graphite-bromine residue compound and the nature of its change at high temperatures are discussed, and a model to explain the peculiar behaviour of the residue compound is proposed. (author)