The electrochemical behavior of Nitroso-R-salt (NRS) in aqueous solutions and the influence of pH are investigated. In alkaline solution, the electrode reaction of NRS exhibits stagnant electrode kinetics. With rising acid concentration, it exhibits more and more fast electrode kinetics and a diffusion-controlled process. Thus, acidic aqueous solutions are favorable for the NRS as active species of a redox flow battery (RFB). Average coulombic and energy efficiencies of the NRS/Zn RFB are 93.2 and 80.6%, respectively, showing that self-discharge is small. The preliminary exploration shows that the NRS is electrochemically promising for RFB application.