The storage characteristics of LiMn2O4, LiCoO2 and LiNiO2 have been evaluated in liquid electrolytes commonly used in lithium-ion batteries. All materials show self-discharge phenomena even at moderate oxidation levels. Three mechanisms are thought to be operating in this process : (a) electrolyte decomposition; (b) spontaneous Li+ reinsertion due to instability of the delithiated cathodes; (c) solubility by corrosion. Mechanisms (a) and (c) have been much in evidence in the impedance tests.