In this paper, a mathematical model for the removal of volatiles from lignite grains is presented. Total amount of volatiles in the dry lignite, experimentally determined, is 44.53%.Such high presence of volatiles makes the lignite reach its ignition temperature very quickly. Methodology of this research is based on laboratory research and the designing of the model for devolution, based  on famous equations of different authors, and the programs Microsoft Excel and Mathlab. Results of the simulation are generated for grains with varying activation energy. Distribution function is continuous (E) with f(E)dE which represents the fraction of possible released volatiles Wj,lim with activation energy within E and E+dE.