Porous anodic oxide films for functional electronic devices. Surface oxide films are formed on metals such as aluminum and titanium by oxidation in electrochemical cells, or "anodizing." Under the right conditions, the films consist of highly regular arrangements of pores with submicron diameters, and can be used to create a wide range of electronic devices. These devices exploit the easy fabrication of the porous films, as well as their high internal surface area, uniform pore size, and the ability to control the pore dimensions for a given application through the electrochemical conditions of anodizing. A particularly promising example of such a device is the dye-sensitized solar cell based on porous semiconducting titanium oxide. Until now the mechanisms of porous oxide growth have not been well understood. However, our modeling and experimental studies have led to significant insight into this process. We have developed criteria that specify the conditions needed for formation of ordered porous films on a wide variety of materials.