Coal composition is popularly characterized in terms of macerals which are the microscopically recognizable individual constituents of coal; petrographic studies are mainly used for determining coal quality, coking properties and composition or coal rank (Taylor et al., 1998); maceral analysis can be carried out using manual and automated techniques, although both have drawbacks. Manual analysis is time consuming and unavoidably subjective, especially when comparing results of different analysts. Automated analysis is one possible alternative to manual analysis but is not without its difficulties, especially when resolving the various macerals from each other and from the support media used to suspend the coal in a polished block; the smallest microscopically recognizable entities in coal are called macerals, they are analogous to minerals in rocks. However they differ since minerals have an homogeneous chemistry and an orderly internal structure. Coal macerals are distinguished by their optical characteristics of color, relief of the polished surface, morphology, reflectance and fluorescence. A coal reflectogram (histogram) provides the reflectance distribution of coal sample in the form of a frequency histogram, the present work aims to study the macerals histograms in order to implemented this tool in petrographic analysis and coal characterization.