Li1.03Co0.15Mn1.82O4 powders as cathode materials used in lithium-ion battery were synthesized using an ultrasonic spray pyrolysis process. The prepared powders were heated at 750 degrees C for different heating durations. As the heating time increased, the crystallinity of the powders significantly enhanced. The nanometered primary particles were aggregated into sphere-like secondary particles with a porous structure. The surface area of the heated samples decreased with an increase in the heating time. After the characteristics of electrochemical performance, the powders heated for 4 h exhibited improved properties. When the discharge rate was 60 C, this sample revealed high capacity retention which was 87% with the reference of 0.1 C. According to the results of high C-rate tests, the electrochemical characteristic of the prepared Li1.03Co0.15Mn1.82O4 powders were found to depend on not only the crystallinity but also the surface area. For preparing cathode materials with good rate capability, the crystallinity and surface area of the materials need to be well controlled. (C) 2008 Elsevier B.V. All rights reserved.