Differential thermal analysis (DTA) and thermogravimetric analysis (TGA) studies have been carried out to investigate the thermal behaviour of Bangladeshi coals. On heat-treatment in an inert atmosphere up to 600 degrees C, 20-27% weight loss occurs due to the removal of various volatile materials. DTA results indicate the chemical reactivity of the coal samples initially at 80-110 degrees C, due to loss of water, and two other major reactions at around 420 and 530 degrees C, due to primary and secondary devolatization. Primary devolatization takes place as the coal melts under the action of heat, and the secondary devolatization represents the resolidification of the coal samples. The DTA curves also indicate the coking ability of the coals.