The present paper entails the petrographic characterization on limited coal samples drawn from the Tarakan basin, Eastern Kalimantan, Indonesia. These coals contain a high concentration of huminite which, in turn, is dominated by telohuminite. As a result of telohuminite content they have high GI and TPI values. They contain, low concentrations of liptinite and inertinite macerals. The dominant microlithotype is vitrite. Based on the macerals and microlithotypes of these coals, their pateodepositional environment has been reconstructed. Accordingly it is deciphered that these coals have originated under telmatic condition. There was predominance of wood derived tissues and increased subsidence rate prevailed in the basin. Moreover, during the time of their evolution, there were alternate phases of oxic and anoxic moor conditions with intermittent moderate to high flooding in the basin. (C) 2009 Elsevier B.V. All rights reserved.