The physical and chemical texture of tectonically deformed coals produced by various formational mechanisms are different from those of primary coals,thus resulting in major differences among the physical properties of the reservoirs of these coals. We have studied the adsorption/desorption be-havior of tectonically deformed coals by the use of isothermal adsorption/desorption experiments un-der equilibrium moisture condition. Experiments of isothermal adsorption/desorption of methane or multi-component gases have indicated that,the adsorption curves of coals with a low degree of tec-tonic deformation conform to the type of isothermal adsorption curve described by the Langmuir equation; the methane adsorption curves of coals with strong tectonic deformation cannot be de-scribed by the Langmuir equation. The adsorption/desorption process of methane and multi-compo-nent gases in the deformed coals is not consistent with primary coals,which form an effect of hys-teresis in different kinds of tectonically deformed coals. With the change of pore structure of tectoni-cally deformed coals at reservoir condition,the added adsorbed CH4 in the experiments is desorbed on the pore surface of coals during the pressure reduction process. Thus,the result shows that the ad-sorption volume in the process of desorbing is greater than that in adsorbing. Because of the defor-mation,structural change,and transformation of the adsorption potential field of coals,it is essential to form a new kind of isothermal adsorption curve and the hysteresis effect of the desorption process. The physical and chemical texture of tectonically deformed coals produced by various formational mechanisms are different from those of primary coals, thereby resulting in major differences among the physical properties of the reservoirs of these coals. We have studied the adsorption / desorption be-havior of tectonically deformed coals by the use of isothermal adsorption / desorption experiments un-der equilibrium moisture condition. Experiments of isothermal adsorption / desorption of methane or multi-component gases have indicated that, the adsorption curves of coals with a low degree of tec-tonic deformation conform The type of isothermal adsorption curve described by the Langmuir equation; the methane adsorption curves of coals with strong tectonic deformation can not be de-scribed by the Langmuir equation. The adsorption / desorption process of methane and multi-compo-nent gases in the deformed coals is not consistent with primary coals, which form an effect of hys-teresis in different kinds of tectonically deformed coals. With the change of pore structure of tectoni-cally deformed coals at reservoir condition, the added adsorbed CH4 in the experiments is desorbed on the pore surface of coals during the pressure reduction process. Thus, the result shows that the ad -sorption volume in the process of desorbing is greater than that in adsorbing. Because of the defor-mation, structural change, and transformation of the adsorption potential field of coals, it is essential to form a new kind of isothermal adsorption curve and the hysteresis effect of the desorption process.