A family of potassium-doped manganese oxide materials were synthesized with the stoichiometric formula Li0.9-XKXMn2O4, where X = 0.0-0.25 and evaluated for their viability as a cathode material for a rechargeable lithium battery. A performance maximum was found at X = 0.1 where the initial specific capacity for the lithium-potassium-doped manganese dioxide electrochemical couple was 130mAh g(-1) of active cathode material. The discharge capacity of the system was maintained through 90 cycles (95% initial capacity). Additionally, the capacity was maintained at greater than 90% initial discharge through 200 cycles. Other variants demonstrated greater than 75% initial discharge through 200 cycles at comparable capacity. (c) 2005 Elsevier B.V. All rights reserved.