Redox Flow Batteries RFBs represent one class of electrochemical energy storage devices in which the energy is stored using chemical reduction and oxidation processes. Here we use the electrochemical quartz microbalance (EQCM) to explore the reaction mechanisms between vanadium species and electrospun carbon-based electrodes. This is a pioneering study on using EQCM technique for the first time to understand the interactions electrode surface and redox-active species in redox flow cells. Understanding the redox processes in flow batteries and interaction electrode –active species is key to accelerate the development of this technology.