We report the formation of high-aspect ratio rod-like structures or 'nano-noodles' of alumina or titania. Such structures are formed either by rapid anodization of aluminum/titanium foil or by long-term post-anodization treatment of porous templates. Specifically, the nano-noodle structures form during anodization in highly acidic electrolytes and/or at high anodization voltages, or when porous templates are etched for long periods of time in an acid. Growth mechanism for such structures is also proposed.