Substituted layered sodium manganese oxide bronzes with the P2 structure were prepared by glycine-nitrate combustion synthesis. The Na in the as-prepared materials could be completely ion-exchanged for Li under mild conditions. All lithium manganese oxide compounds obtained after ion-exchange have O2 stacking of the layers. Cyclic voltammetry and stepped potential experiments on lithium cells containing these materials show that the main redox reaction around 3.1 V is a diffusion-controlled process and is completely reversible. O2-Li-0.6[Al(0.1)Mn(0.85)square(0.05)]O-2 and O2-Li-0.6[Ni(0.1)Mn(0.85)square(0.05)]O-2 are particularly promising as cathode materials in lithium cells because of the high reversible discharge capacities (180 mAh/g). (C) 2003 Elsevier Science B.V. All rights reserved.