Semiempirical PM6 quantum mechanical method was used to investigate the changes in the electronic and physical parameters of graphene before and after interaction with calcium oxide (CaO). Calculations were conducted the optimized structures with graphene interacting with two CaO molecules forming G/CaO nanocomposite once through the O atom then through the Ca atom, in the form of adsorb and complex states. Results indicated the deformation of graphene structure upon interaction with CaO but the resulting G/CaO is more thermally stable than graphene itself. The studied G/CaO composites were also found to be more reactive than graphene in regard to their higher calculated total dipole moments. The calculated thermal parameters further confirmed the thermal stability of G/CaO composites.