Ru nanotubes were fabricated by atomic layer deposition (ALD) using bis(ethylcyclopentadienyl)ruthenium and oxygen onto an anodized aluminum oxide (AAO) template with a diameter of 50 nm and an aspect ratio of 10. The wall thickness of the Ru nanotubes could be precisely controlled from 13 to 23 nm by adjusting the number of ALD cycles. Transmission electron microscopy analysis revealed that the maximum density of the Ru nuclei on the alumina surface was as high as 1.8x10(12) cm(-2) at 180 ALD cycles, and was thereby responsible for the conformal deposition of Ru inside the pore wall of the AAO template. (c) 2008 The Electrochemical Society.