Hydrated amorphous FePO4 was synthesized by a sonochemical reaction method, in which a solution of (NH4)(2)HPO4 and FeSO4.7H(2)O was irradiated by an ultrasonic wave. From this material, two kinds of cathode materials were easily prepared: (1) an amorphous sample prepared by heating at 350 degrees C and (2) a crystalline sample prepared by heating at 700 degrees C. Both samples consisted of homogeneous sub-micron particles. The amorphous sample of FePO4 exhibited high discharge capacities with more than 100 mAh g(-1) in the range of 3.9-2.0 V versus Li/Li+ at a current rate of 0.2 C. The sonochemical synthesis proposed herein has the following advantages: no use of oxidation agents for production of trivalent iron ions, reduction in reaction time, control of particle size, and enlargement in surface area for the preparation of the cathode material. (C) 2007 Elsevier Ltd. All rights reserved.