Arrays of Ni nanoparticle chains embedded in TiO2 nanotubes (TiO2/Ni) were fabricated by one-step electrodeposition in anodic aluminum oxide membranes. The formation of spacing Ni nanoparticles or continuous nanorods in the TiO2 nanotubes depends on the deposition potential, the potential waveform. and the pH value in the electrolyte. The growth mechanism is attributed to the generation of H-2 bubbles and their periodical evolution outside of the TiO2 nanotubes. (C) 2009 Elsevier Ltd. All rights reserved.