Well-organized TiO2 nanotube arrays are synthesized by anodic oxidation and then modified with MoO3 via facile electrodeposition for their improved Li-ion intercalation property. All the bare and MoO3-deposited TiO2 nanotubes are cycled at a current of 50 or 200 μA cm−2. The deposited nanotubes surprisingly deliver twice or even triple areal capacity of the bare ones, as well as better rate capability. For example, the bare nanotubes exhibit an initial capacity of 81.2 μAh cm−2 and a final capacity of 59.6 μAh cm−2 over 48 electrochemical cycles, while the ones coated by MoO3 using only one deposition cycle displays a nearly doubled initial capacity of 154.9 μAh cm−2 and a final capacity of 116.6 μAh cm−2. More deposition cycles yield TiO2 nanotubes with higher capacities up to 204.7 μAh cm−2. Such improvement could be further optimized by tuning the dimensions of TiO2 nanotubes. An eight-fold increase in the capacity of MoO3/TiO2 nanotube composite anode is achieved easily with larger nanotubes for MoO3 coating. This is attributed to the combination of MoO3 with a high specific capacity and TiO2 nanotubes with large surface area allowing efficient MoO3 deposition and ionic transport inside the anode.