The presence of dissolved oxygen inhibits the anodic dissolution of titanium, predominantly in the active range. The reduction rate of oxygen partially limited by its diffusion is shown to depend on the potential and to be localized on active islets each one of which has its own diffusion layer. A mixed kinetics for this reduction reaction is observed in the active range and a pure diffusional one in the near passivity range. The corrosion morphologies are correlated with the various kinetics and localizations observed for the oxygen reduction.