Incorporation of silicon species from an alloy substrate into anodic titania is shown to stabilise the structure of the film, facilitating investigation of the ionic transport processes in amorphous titania grown at high efficiency. Thus, an amorphous anodic film developed on a sputtering-deposited Ti–6 at.%Si alloy formed to 100 V in phosphoric acid electrolyte in contrast to a partially crystalline film developed on relatively pure titanium at