The electrochemical performance of LiCoPO4-based electrodes was studied in dependence on synthetic conditions,. The role of particle size distribution is illustrated. Structural changes occurring at lithium extraction-insertion were explored by ex situ and in situ synchrotron XRD measurements. For the samples annealed at temperature lower than 600 degrees C the amorphisation of the cathode material was identified. For a high-temperature sample the two-phase character of electrochemical reaction was confirmed. The character of structural changes observed at charge and discharge is different: the two-phase reaction LiCoPO4-"COPO4" occurs during charging, while discharge induces a strong increase of the cell volume for the Li-poor phase. (c) 2005 Elsevier B.V. All rights reserved.