Anodization was performed in phosphate and fluoride containing electrolytes at different pH and sweep rates with the aim of analyzing the variation in current density during the process continuously. The effect of pH and sweep rate on the morphology of titanium dioxide (TiO2) nanotubes, grown on Ti-6Al-4V alloy, has been explicitly examined in this study. At the same time a microscopic analysis of the different stages of the formation of the nanotubes was performed. A new perspective to the growth mechanisms of the nanotubes was brought about in this study. The morphology of the nanotubes was closely related to the density of initial etching sites. (c) 2015 The Electrochemical Society. All rights reserved.