This work presents the effect of specific gravity of coal on its combustion characteristics. Coals with different specific gravity fractions represented by the arithmetic mean specific gravity (MSG) in the range of 1.35 to 2.0 were prepared by sink–float based density separation from run-of-mine (ROM) coal. The characterization of coal with different MSG was done using proximate, ultimate, and gross calorific value (GCV) analysis. Thermogravimetric analysis and differential thermogravimetry (TGA-DTG) studies of coals with different MSG were carried out in oxygen atmosphere to analyze their combustion characteristics. Various burning profile parameters (Ti, Tp, Tf, DTGmax) were assessed to identify the impacts of MSG of coals on their combustion characteristics. Further, different combustion indices (Di, Df, S, Hf) were evaluated to get the insights of combustion. Based on the experimental results, it was observed that, with an increase in coal MSG from 1.35 to 2.0, GCV decreased from 7426 to 3625 kcal/kg, Ti varied from 355 to 412 °C, Tp varied between 466 and 487 °C, and DTGmax decreased from 6.73 to 4.83 wt%/min. The result signifies that with an increase in MSG of coal, its combustion properties weaken. The activation energy for combustion varied between 93 and 119 kJ/mol. Based on the present analysis, it may be observed that lower MSG coals have enhanced combustion characteristics than higher MSG coals.