The thermal properties of Li4/3Ti5/3O4 and Li1+x Mn2O4 electrodes were investigated by isothermal micro-calorimetry (IMC). The 150-mAhg−1 capacity of a Li/Li4/3Ti5/3O4 half cell was obtained through the voltage plateau that occurs at 1.55V during the phase transition from spinel to rock salt. Extra capacity below 1.0V was attributed to the generation of a new phase. The small and constant entropy change of Li4/3Ti5/3O4 during the spinel/rock-salt phase transition indicated its good thermal stability. Accelerated rate calorimetry confirmed that Li4/3Ti5/3O4 has better thermal characteristics than graphite. The IMC results for a Li/Li1+x Mn2O4 half cell indicated less heat variation due to the suppression of the order/disorder change by lithium doping. The heat profiles of the Li4/3Ti5/3O4/Li1+x Mn2O4 full cell indicated less heat generation compared with a mesocarbon-microbead graphite/Li1+x Mn2O4 cell.