Effect of NaAc on the anodic growth of TiO2 nanotube arrays is described. NaAc-added approach yields longer nanotubes relative to samples grown from NaAc-free electrolyte. And the growth rate of TiO2 nanotubes has pH independency in NaAc-added electrolytes. The key to achieve a high aspect ratio TiO2 nanotube arrays is to decrease the chemical dissolution rate at the mouth of the tube by adding NaAc as protective coating. Adsorption of Ac- species on the TiO2 surface is shown to markedly decrease the chemical dissolution rate of the tube mouth, resulting in longer nanotube length.