Herein, we demonstrate that the potential difference of proton reduction and hydrogen gas oxidation of protic ionic liquids is closely related to the proton exchange rate in the electrolyte. Through a careful design of anion chemistry, the proton exchange rate can be boosted by several orders of magnitude, reaching 200 kHz at 100 °C. It is found that the enhanced proton exchange rate can effectively decrease the potential loss at the electrode, most likely through alleviating the H+ concentration gradient incurred by electrochemical reactions at the electrode surfaces. This research therefore highlights the strategy of using anions of medium-strength acids, such as H2PO4-, for protic ionic liquids with enhanced proton exchange capability.