Internal combustion type spray pyrolysis apparatus was used to prepare cathode materials for lithium ion batteries. Spherical LiNi0.5Mn1.5O4 precursor powders with an average size of about 2 m were successfully produced by this technique. After calcination at 800°C, LiNi0.5Mn1.5O4 precursor powders crystallized to a spinel structure. The spherical morphology changed to an irregular morphology at temperatures higher than 900°C. The discharge capacity of the LiNi0.5Mn1.5O4 cathode was 130 mAh/g at 1C. After 300 cycles at 1C, 90% of the initial discharge capacity was maintained, and after 100 cycles at 6C, 70% of the discharge capacity at 1C was maintained.