Nanowire-structured MnO2 active materials were prepared by a chemical precipitation method and their supercapacitive properties for use in the electrodes of supercapacitors were investigated by means of cyclic voltammetry in an aqueous gel electrolytes consisting of 1M Na2SO4 and fumed silica (SiO2). The MnO2 electrode showed a maximum specific capacitance of 151Fg−1 after 1000 cycles at 100mVs−1 when using the gel electrolyte containing 3wt.% of SiO2, which is higher than 121Fg−1 obtained when using the 1M Na2SO4 liquid electrolyte alone.