Abstract: The synthesis of reduced graphene oxide nanoparticles includes the steps of: mixing soot with an acid to obtain a solution; adding a first oxidant gradually into the solution to oxidize the carbon source and obtain a suspension; stirring the suspension while maintaining a temperature of the suspension at about 35° C.; raising the temperature of the suspension to about 60° C.; adding water into the solution; adding a second oxidant into the suspension while stirring resulting in the oxidation of the carbon source to form the reduced graphene oxide nanoparticles; and isolating the resulting reduced graphene oxide nanoparticles by centrifugation. The acid is preferably an acid mixture including, for example, sulfuric acid (H2SO4) and phosphoric acid (H3PO4). The first and second oxidants can be potassium permanganate (KMnO4) or hydrogen peroxide (H2O2).