We report on the uniform anti-reflection coating of TiO2 nanotube layers with a secondary material – indium trioxide (In2O3) – by Atomic Layer Deposition (ALD). We provide for the first time the detailed evidence of the ALD deposited coating inside nano-tubes for three different tube layers with aspect ratio up to ≈80, which is so far the highest aspect ratio reported for ALD-processed self-organized anodic TiO2 nanotubes. We show that uniform In2O3 coating of the nanotubes strongly influences the overall reflectance of the layers due to intrinsic properties of In2O3.