Considered are the thermodynamic conditions on the surfaces generated in coal cracks in the process of its destruction. It is shown that the temperature at the surface of cracks on the stage of destruction is comparable with the melting temperature of coal and ignition of methane. Ratios for the assessment of the development phase transitions on the surfaces of coal cracks. It is shown that the rate of methane in proportion to the total surface of the pieces of coal at de-struction. To reduce the amount of methane generation it is recommended to reduce the load on the breakage face.