A novel method for increasing the transparency of an anodic aluminum oxide film on glass is demonstrated. The residual aluminum layer, which limits the transparency of the porous aluminum oxide film, was fully converted to its oxide by the ion-drift process. The transmittance of the film was improved more than 20% over the visible-near infrared range and was similar to that of a glass substrate. This ion-drift process also improved the adhesion of the anodic alumina film to the glass substrate. (C) 2005 The Electrochemical Society.