Nanostructured Sb-doped SnO2 (ATO) thin films were prepared by radio frequency magnetron sputtering, and their electrochemical properties were evaluated versus Li metal in Li/electrolyte/ATO cells. The ATO film electrodes show high specific capacity, stable cycling performance and good rate performance. Discharge capacities were 1482, 973, 636, and 447mAhg−1 for the first, second, 100th and 200th cycles, respectively. Electrochemical reaction products of ATO films in the cell were examined by analyzing the phase evolution of the ATO electrodes electrochemically induced at various stages using high resolution transmission electron microscopy. The results reveal the electrochemical reaction as follows: the decomposition of SnO2 and formation of metallic Sn and Li-Sn alloy during discharge process; reversible de-alloying of Li-Sn, reaction between Sn and Li2O, and even partial formation of SnO2 during charge process. Nano-structured characteristics were maintained during the charge-discharge processes, to which good electrochemical performance of the ATO thin films is mainly attributed.