Abstract: The free but intermittent sources of energy such as photovoltaic and wind energy has become more popular nowadays. The installation of this type of power source usually requires a secondary power source, often the energy storage system such as battery to smoothen power output over time. In this article, we introduce, an alternative energy storage system, an organic-electrolyte redox flow battery (RFB), which uses anthraquinone-2-sulfonic acid (AQS) and 1,2-benzoquinone-3,5-disulfonic acid (BQDS) as the electrolytes. The membrane is coated with Vulcan carbon using an ultrasonic spray technique allowing for higher current density. The polarization curve of this system has shown that the RFB with organic AQS and BQDS has impressive amount of energy density, and can deliver the maximum current density up to 45 mA/cm 2 and the maximum power density up to 4 mW/cm 2 . At 5 mA/cm 2 current density, the power delivery has the current efficiency and energy efficiency of 96% and 48%, respectively.