Size dependent electrochemical properties of reduced graphite oxide are investigated. Two kinds, 5 and 149 mu m, of natural graphite as a precursor are used to synthesize graphite oxide and to reduce it by hydrazine. The precursor of smaller grain size provides efficient oxidation and reduction, resulting in improved electrochemical properties compared to the precursor of larger grain size for energy storage applications. Furthermore, the influence of hydrazine concentration on the reduction is investigated, finding that too much hydrazine causes side effects on the reduction. (C) 2014 Elsevier B.V. All rights reserved.