Fabrication of anodic aluminum oxide (AAO) on 4 in. glass substrate was demonstrated. Using unique structure with quadruple contacts as electrode support during anodization, we reported gradual transformation from opaque aluminum to transparent AAO over the entire substrate. In contrast, partial transformation was observed with typical single contact approach where growth of insulating AAO inhibited subsequent anodization by interrupting current flow from the contact point. Results from optical spectroscope revealed moderate reduction in transmittance after AAO formation. Successful development of large-area AAO on glass substrate opens up opportunities for AAO templated devices that require a large footprint. (c) 2007 The Electrochemical Society.