TiO2 nanotubes were successfully prepared based on rapid breakdown anodizat ion (RBA) without halogen ions. Typically, ethylene glycol (EG) containing hydrated oxalic acid, high temperature (>50 degrees C), and high potential (>80 V) are required to produce RBA nanotubes without halogen ions. However, the restricted electrochemical conditions were changed significantly with each factor. The primary ions for the local breakdown of the anodic oxide to generate RBA nanotubes were attributed to the small amount of OH center dot generated from the dissociation of hydrated oxalic acid. Local breakdown of the oxide was enhanced using low viscosity EG, a high temperature, and high applied potential. However, if the temperature was greater than 100 degrees C, a flat barrier-type oxide without RBA nanotubes was generated because of evaporation of H2O. In addition, too high potential led to a damaged oxide instead of the RBA nanotubes. All electrochemical conditions for the RBA nanotubes formations showed certain current density ranges during the anodization. A map for the formation of RBA nanotubes was suggested for selected electrochemical conditions. (C) 2015 The Electrochemical Society. All rights reserved.