The method of producing hydrogen peroxide using nanostructured bismuth oxide is an electrochemical process for producing hydrogen peroxide using a cathode formed as oxygen-deficient nanostructured bismuth oxide deposited as a film on the surface of a conducting substrate. An anode and the cathode are immersed in an alkaline solution saturated with oxygen in an electrolytic cell. An electrical potential is established across the cathode and the anode to initiate electrochemical reduction of the oxygen in the alkaline solution to produce hydrogen peroxide by oxygen reduction reaction.