A wide range of coal ranks from lignite to anthracite has been investigated using thermogravimetric analysis (TGA). The derivative peak maximum for volatile matter evolution shows a strong correlation (r(2) = 0.998) with vitrinite reflectance, thereby providing a convenient measure of degree of coalification (coal rank) without requiring the equipment of and more time-consuming petrographic analysis. T-max by the Rock-Eval method also shows a positive although somewhat poorer correlation (r(2) = 0.856) with vitrinite reflectance. TGA also reproduces the components of the proximate analysis of coal.