The structure and electrochemical properties of LiAl y Co1−y O2 cathodes for Li rechargeable batteries have been closely examined by neutron diffraction, X-ray diffraction (XRD), X-ray absorption spectroscopy (XAS), differential scanning calorimetry (DSC), and electrochemical methods. Neutron diffraction patterns and Co K-edge X-ray absorption near-edge structure (XANES) spectra of LiAl0.25Co0.75O2 revealed that aluminum and cobalt ions were statistically distributed in octahedral 3b sites of the ordered α-NaFeO2 structure. The DSC scan of Li0.5Al0.25Co0.75O2 showed an increase in the peak temperature and reduction in the exothermic peak compared to those of Li0.5CoO2, and it indicates that Al-doped LiCoO2 shows the good thermal stability of the cathode and reduction of the heat of reaction.