Graphite microparticles (d50 6.20 m) were oxidized by strong acids and the resultant graphite oxide was thermally exfoliated to graphene oxide sheets (MPGO, C/O 1.53). Graphene oxide was treated with non-thermal plasma under SO2 atmosphere, at room temperature. The XPS spectrum showed that SO2 was inserted only as the oxidized intermediate at 168.7 eV in the S2p region. Short thermal shocks at 600 and 400 oC, under Ar atmosphere, produced reduced sulfur and carbon dioxide as shown by XPS spectrum and TGA analysis coupled to FTIR. MPGO was also submitted to thermal reaction with SO2 at 630 oC, and the XPS spectrum in the S2p region at 164.0 eV showed that this time only the non-oxidized episulfide intermediate was inserted. Plasma and thermal treatment produced partial reduction of MPGO. The sequence of thermal reaction followed by plasma treatment inserted both sulfur intermediates. Since oxidized and non-oxidized intermediates have different reactivities, this selective insertion would allow adding selective types of organic fragments onto the surface of graphene oxide.