Layered Li[Ni0.5Mn0.5]O-2 materials with high homogeneity and crystallinity were prepared using high speed ball milling. The Li[Ni0.5Mn0.5]O-2 electrode delivered a high discharge capacity of 152 mA h g (-1) between 2.8 and 4.3 V with excellent cycleability. The TEM analysis showed that the Li[Ni-0.5.Mn-0.5]O-2 electrode went through a considerable morphological change without altering its initial layered structure while the electrode retained its initial discharge capacity even after 50 cycles. (C) 2003 Elsevier Science Ltd. All rights reserved.