Sub-bituminous coals of Ramagundam coal field have been studied to know their petrographic and chemical composition. Based on the petrographic characters, an attempt has been made to understand their depositional environment. These coals are characterized by low to medium moisture and volatile matter contents. Inertinite is the dominant maceral group followed by vitrinite and liptinite and the coal contains significantly elevated inorganic content. The study reveals that they have originated from forest swamps under a mildly oxic to anoxic environment with conditions favorable for tissue preservation.