LiCoO2 particles were coated with various wt.% of lanthanum aluminum garnets (3LaAlO3:Al2O3) by an in situ sol–gel process, followed by calcination at 1123K for 12h in air. X-ray diffraction (XRD) patterns confirmed the formation of a 3LaAlO3:Al2O3 compound and the in situ sol–gel process synthesized 3LaAlO3:Al2O3-coated LiCoO2 was a single-phase hexagonal α-NaFeO2-type structure of the core material without any modification. Scanning electron microscope (SEM) images revealed a modification of the surface of the cathode particles. Transmission electron microscope (TEM) images exposed that the surface of the core material was coated with a uniform compact layer of 3LaAlO3:Al2O3, which had an average thickness of 40nm. Galvanostatic cycling studies demonstrated that the 1.0wt.% 3LaAlO3:Al2O3-coated LiCoO2 cathode showed excellent cycle stability of 182 cycles, which was much higher than the 38 cycles sustained by the pristine LiCoO2 cathode material when it was charged at 4.4V.