Carbonization behaviour of original and demineralized lignites originating from different parts of Turkiye was investigated using thermogravimetry technique. Experiments were conducted in nitrogen atmosphere at a constant heating rate of 40 K/min. The TG and DTG curves of original and demineralized lignites which obtained under identical conditions were compared and discussed. It was observed that the mineral matter content of lignites plays an important role in determining their carbonization characteristics. The shape of carbonization TG curves were strongly effected from the demineralization process.