In this study, the combined density functional theory (DFT) and molecular dynamics (MD) simulation methods were carried out to investigate the potential capability of uranium-decorated graphene (U-G) for the separation of deuterium from hydrogen gases. Graphene with hexagonal honeycomb lattice arrangement is suitable for adsorption of individual uranium atoms, with a high binding energy (-1.173 eV) and U-U distance longer than 7 angstrom. This U-G system has ability to hold up to six H-2(5.16% wt) or seven D-2(11.75% wt) molecules per U atoms. To gain further insights into these interactions, partial electronic density of states (PDOS) and the electron density distribution of the elements were analyzed. The MD results are in reasonable agreement with the results obtained by DFT method. Our calculated results indicate that at room temperature, D-2 molecule has higher affinity for U-G system than the H-2 molecule. In order to increase the D-2 separation factor from H-2 , the effect of temperature was studied. The results indicated that adsorption ratio of D(2 )to H-2 increases by decreasing the temperature.