The electrochemical synthesis of ozone is studied on lead dioxide electrodes in sulfuric acid solutions. The two maximums of the current efficiency for ozone (CEO) observed at 2–3.5 V are largely due to the participation of various chemisorbed particles in the ozone synthesis. In the vicinity of the first CEO maximum at lead dioxide, ozone forms only in a discharge of water molecules with the participation of adsorbed oxygen-containing radicals. In the potential range of the second maximum, the adsorbed anion radicals, e.g., ·HSO4 and ·SO4, also take part in the reaction of ozone generation. At the electrode not subjected to anodic polarization, CEO is considerably higher than that on the preliminarily polarized electrode. On the basis of the experimental data, schemes for the ozone evolution at PbO2 in sulfuric acid at 2 to 3 V are proposed.