Self-aligned titania nanotubes have been fabricated by electrochemical anodic oxidation of titanium foil in organic electrolyte containing fluoride ions. Varying the water content in electrolyte used during anodization results in a fluorine concentration gradient along the titania nanotubes. A consequence of this is the dependence of the extent and morphology of the nanograss layer on the water content in the electrolyte. A mechanism has been proposed for the formation of the nanograss layer over titania nanotubes and its different morphologies viz. ring type or vertical splitting. (C) 2015 Elsevier B.V. All rights reserved.