Various electrochemical techniques have been used to study the electrochemical insertion (extraction) of lithium into (from) multi-walled carbon nanotubes (MWNTs) prepared by catalytic decomposition of ferrocene and xylene. The galvanostatic charge/discharge profiles display a small hysteretic loss and the cyclic voltammograms are quite symmetric in the shape of cathodic and anodic branches, implying that lithium insertion/extraction process is highly reversible. In addition, rate capability and cycleability of charge into the MWNTs are satisfactory. The excellent reversibility and small hysteretic loss of the MWNT are attributed to the extremely pure structural character of the MWNTs with moderate chemical diffusion coefficient of lithium through the structure.