LiNixCo1-xO2 solid solutions are synthesised and their electrochemical performance as cathodes is examined in lithium cells. Through DTA/TG analysis and self-discharge tests, it is found that both the thermal stability at high temperature and the electrochemical stability in the fully-charged state for LiNixCo1-xO2 increases with increasing content of cobalt in the compound. The average operating potentials for the solid solutions are lower than those for purl: LiCoO2. This indicates that both cobalt and nickel take part in the redox reactions during lithium insertion and extraction. The substitution of Ni3+ for Co3+ in LiNixCo1-xO2 can improve the specific capacity, but with a small sacrifice in cycleability. (C) 2000 Elsevier Science S.A. All rights reserved.