Abstract In order to investigate the thermal behaviors of lithium (Li) atom intercalated in and adsorbed on the graphite intercalated compound, the molecular dynamics procedure at molecular mechanics 2 level was applied to the hydrogen terminated cluster model composed of two layers of C 150H 30 plane. On the basis of the optimized structure, one intercalated Li atom was stabilized at the mass center and adsorbed Li was done above the center of upper plane. Both Li atoms initiate to migrate at 50 K parallel to the plane with almost the same migration rate in the temperature range from 50 to 200 K. However, their migration processes are clearly different. The former gets out of the cluster model, drawing the increasing curves accompanied by the induction period in the coordinate axes of the migration distance vs. the simulation time at every temperature. The latter, however, cannot be released from the cluster model below 150 K where it remains on the side face of the cluster model. At 50 and 100 K, it migrates from the center to the circumference periodically cannot escape from the surface of cluster model. Thus, the potential well is considered to be deeper on the surface than in the layers.