Phase pure, homogeneous, and well-crystallized lithium iron phosphate LiFePO4 was synthesized by aqueous co-precipitation of an Fe(II) precursor material and succeeding heat treatment in nitrogen. The particle morphology of the precursor is preserved during the heat treatments. Excellent electrochemical properties in terms of capacity, reversibility, cycling stability and rate capability have been achieved. The thermal stability of charged electrodes is superior versus other positive electrode materials. If reductive synthesis conditions are used in the heat treatments, problems arise from the possible generation of iron phosphide. (C) 2003 Elsevier Science B.V. All rights reserved.