The growth mechanism of TiO2 nanorods fabricated by the anodization of Ti films using a mask of anodic aluminum oxide is investigated by examining the growth rate and morphology of the fabricated nanorods. It is found that the growth rate is 250 nm/s within the first 0.1 s at 117 V and decreases abruptly to 0.79 nm/s after 3 s. In addition, the diameter of the nanorods is larger near the top than near the root of the nanorods. A growth mechanism is proposed to explain these interesting phenomena. (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3496404] All rights reserved.