This article entails results of the study designed to characterize the coals of Ib River coalfield of Mahanadi Valley, Orissa. The study reveals that durain is the dominant lithotype of these coals, which has imparted a dull appearance. This is reflected in its microscopic constituents by the dominance of the macerals of inertinite group and high mineral matter content. This is followed by vitrinite, while liptinites occur in small quantity. Further, it is evolved that these coals are sub-bituminous in rank and have originated from forest and open moors under oxic conditions with intermittent flooding.