Graphene oxide (GO) obtained by Hummers method was functionalized by ethylenediamine (EA) and 1,6-hexanediamine (HA) in N, N-dimethyl formamide using 1, 1, 3, 3-tetramethy-luronium hexafluorophosphate as a coupling agent. The functionalized GO was characterized by elemental analysis, FT-IR, XRD, XPS, TGA, SEM and TEM. Results showed one carbon atom in nine to ten of the carbon atoms in GO was functionalized by an amine group. The thermal stability of the GO functionalized by HA was much higher than the one functionalized by EA. However, the former was less dispersible in N, N-dimethyl formamide than the latter.