In this work, sulfur-doped graphene oxide powders, prepared in one step and at room temperature by chronoamperometry, were used as an additive in the fumed silica-based gel electrolyte of a valve-regulated lead-acid battery. The amount of additives and parameters that affected the performance of the gelled electrolyte was optimized by using electrochemical methods such as cyclic voltammetry, electrochemical impedance spectroscopy, and corrosion tests. Optimum amount of sulfur-doped graphene oxide was determined as 0.6 wt%. Stirring rate and agitation time were also determined as 250 rpm and 60 minutes, respectively. Battery performances of the gelled electrolytes were investigated by cyclic charge-discharge tests. Discharge capacities of the aqueous electrolyte, bare fumed silica-based gel electrolyte, and fumed silica-based gel electrolyte with sulfur-doped graphene oxide were determined as 0.70, 16(-,) and 30 mAh.cm(-2) at 20 mA.cm(-2) charge and discharge current densities, respectively.