Although the coal reservoir has been recognized as one of the target subsurface formations for carbon dioxide (CO₂) sequestration, the long-term behavior of injected CO₂ in coal seams during post-injection period has not be clarified. The purpose of this study is to address this issue. In this study, a numerical model for coupled gas transport and adsorption/desorption behaviour is presented. In particularly, the desorption hysteresis is considered through developing a thermodynamically based adsorption-desorption model. The developed model is firstly validated against experimental tests on gas adsorption/desorption in coals and a good agreement between numerical results and experimental benchmarks is achieved. the developed model is applied to investigation of long-term storage of CO₂ in a target coal seam. The simulation results show that after ceasing CO₂ injection, the gas pressure in the vicinity of the injection well starts to decline due to the CO₂ pressure gradient away from the well, which leads to a reduction in the pressure difference in the domain. Although the differences in gas pressure in the domain after years remain small, the differences in adsorbed CO₂ concentration in the domain is obvious due to desorption hysteresis. It is of significant importance to ensure long-term containment of stored CO₂ and design the operating pressures for a target coal-seam.