Here we report the enhanced solvothermal reduction of graphene oxides using a mixed solution of sulfuric acid and an organic solvent, such as DMF and DMSO. Acid catalyzed dehydration increased the speed of the reduction and the resulting reduced graphene oxides showed less oxygen content and higher electrical conductivity than those reduced with only an organic solvent. The C/O ratio and electrical conductivity increased 1.5 and 6.6 times by using mixed solution. In addition, the reduced graphene oxide prepared by the mixed solution showed highly improved capacitance during the cyclic voltammetry measurement. This approach may provide an effective synthetic method for high quality reduced graphene oxides that can be used in wide range of applications. (C) 2012 Elsevier B.V. All rights reserved.