Anatase titania nanotube arrays were fabricated by means of anodization of Ti foil and annealed at 400°C in respective CO and N2 gases for 3h. Electrochemical impendence spectroscopy study showed that CO annealed arrays possessed a noticeably lower charge-transfer resistance as compared with arrays annealed in N2 gas under otherwise the same conditions. TiO2 nanotube arrays annealed in CO possessed much improved lithium ion intercalation capacity and rate capability than N2 annealed samples. At a high charge/discharge current density of 320mAg−1, the initial discharge capacity in CO annealed arrays was found to be as high as 223mAhg−1, 30% higher than N2 annealed arrays, ∼164mAhg−1. After 50 charge/discharge cycles, the discharge capacity in CO annealed arrays remained at ∼179mAhg−1. The improved intercalation capacity and rate capability could be attributed to the presence of surface defects like Ti–C species and Ti3+ groups with oxygen vacancies, which not only improved the charge-transfer conductivity of the arrays but also possibly promoted phase transition.