We report a feasible and facile approach of coaxial anodic oxidation under dynamic electrolyte conditions for patterning Ti tubes. Uniform TiO 2 nanotube arrays are prepared at the inner surface of Ti tubes with 930 mm in length and 3 mm in diameter, being the largest aspect ratio ever reported. Interestingly, a resulting structure of nanowire bundles standing upright the nanotubes, anodized at 20 V for 4 h with an electrolyte flow rate of 12.2 μL/s, exhibits superhydrophobic feature with a water contact angle of 165° and sliding angle of