Ultrahigh-aspect-ratio titania nanotubes are fabricated electrochemically in organic-acid-containing chlorine salts. The tubes (see figure) are several tens of micrometers in length and only about 20 nm in diameter. The use of organic acids as anodic electrolyte combined with the vigorous chlorine chemistry result in the incorporation of a significant amount of carbon into the nanotubes. Such high-aspect-ratio nanotubes are shown to have enhanced visible-light-harvesting characteristics.