Abstract: LiCoO₂ ceramics were synthesized by solid state reaction. An internal friction peak of phase transition type was observed around 170 K for LiCoO₂ ceramics via dynamic mechanical analysis (DMA) in the temperature range of 123-573 K, which corresponds to the turning point in the plot of the logarithm of conductivity versus the inverse of temperature (ln σ-1/T). It shows that the phase transition at 170 K could change the electronic transport property and the activation energy doubles in the high temperature portion in LiCoO₂ .