Comparative analysis of two LiCoO 2 powders with mean grain size 3–5μm and 50–60nm, obtained by freeze drying synthesis, is performed. Both samples belong to high temperature (HT) hexagonal modification of LiCoO 2 and display good crystallinity by XRD while local electron diffraction patterns indicate the traces of disorder in the nanocrystalline powder. Differential capacity versus voltage curves of nanosized LiCoO 2 demonstrate perfect reproducibility of Li intercalation since 1st cycle. Electrochemical capacity of nanomaterial is decreased to 115mAh/g during first cycles with little or no further changes. Dependence of the electrochemical performance on the grain size is referred to the existence of distorted areas in the nanocrystalline sample.