In this paper, the results of a laboratory study on the effect of coal metamorphism degree and the methane pressure gradient on gas desorption are presented. Sorption-desorption equilibrium states were investigated with coal samples formed in cubes (15 x 15 x 5 mm) with simultaneous kinetic studies of sorption and dilatometric processes within a gas pressure range of 4.5 MPa up to about 0.1 MPa. The results obtained show that the highest gain of the desorbed gas amount per unitary pressure drop corresponds to pressure values close to atmospheric and the lowest extent of sorption-desorption is obtained for the Polish coals, V-daf, which amounts to 20-40%.