XRD measurements were carried out for 10 types of coal chars deashed with HCl and heat-treated at different temperatures. Among structural parameters estimated by STAC-XRD method, 'average number of aromatic layers in a stack' and 'stacking index' corresponded well to gasification parameters of chars prepared at 1500C. Such a good relationship was not found for champles prepared at the same temperature, but without acid treatment. Accordingly, gasification behavior of char can be numerically related to the stacking structure of aromatic layers under a deashed condition.
