The antioxidant protective properties of polyaromatic organic layers were evaluated toward reactive oxygen species (ROS) using scanning electrochemical microscopy in a foot-printing strategy. The layers were prepared by electrografting of aryldiazonium salts. Where p-(methyl)phenyl films show only weak protective properties toward ROS, p-(ethynyl)phenyl films evidence efficient protection of the covered surfaces. Applied potentials and electrolytes used during oxygen reduction reaction are critical parameters to control, prevent, or reduce the influence of ROS production and hence enhance the device lifetime.