X-ray diffraction (XRD) analysis provides the information on carbon structure in coal. We have developed a standardized procedure to obtain some structural parameters from the XRD profiles, i.e., average number of layer stacking, layer distance and a ratio of stacking layers in coal. The difference between the data collected according to this procedure at three different research institutes was evaluated statistically. It was found that coals with grown layer stacking had higher ordered layer structure, but that this ordering had the limit.
