Reduced graphite oxide (RGO) is prospective for application as an active material for supercapacitor electrodes due to the simple synthesis, the high specific surface area and the presence of oxygen-containing functional groups. Functionalization of such materials affects hydrophilicity, surface morphology and contributes to the redox processes when potential is applied. In this article RGO was treatment by mixture of potassium hydroxide and chloroacetic acid; hydrobromic acid and oxalic acid; in various ratio of strong nitric, sulfuric and phosphoric acids. Such functionalization of RGO leads to decrease in particle size, increase the quantity of oxygen-containing groups on the surface of the materials and affects the change of carbon hybridization from sp2 to sp3. Furthermore, all the samples were investigated by cyclic voltammetry (CV) to study the redox processes occurring on the electrode material surface. The peaks on the CV curves were compared with the corresponding redox reversible reactions. Furthermore, the specific capacity of all samples was calculated. Thus, at low carboxylation level of RGO specific capacity is increased due to significant contribution of redox processes while high functionalization leads to decrease in conductivity and, as well in specific capacity.