Undoped Mn3O4 shows relatively poor performance as a possible anode material on reversible reaction with lithium. A dramatic increase in cyclability is obtained on partial substitution of Mn by Co. Data are presented for the composition Mn2.6Co0.4O4, which, after the first cycle, shows essentially constant capacity of 400 mAh g(-1) at similar to0.6 V (C) 2004 Elsevier B.V. All rights reserved.