The influence of the electrolyte alkaline ions, potassium, lithium, and sodium, on the efficiency of the Na0.6CoO2 phase, as a conductive additive in the positive nickel oxide electrode, is analyzed in the present paper. Aging tests of the Na0.6CoO2 phase and of the gamma-Co phases, deriving from it, in the three electrolyte components, KOH, NaOH, and LiOH, have shown the presence of topotactic exchange/(de)intercalation reactions of the alkaline ions, occurring within the materials. Electrochemical tests, performed in the various electrolytes, underline an unfavorable effect of lithium ions. The formation of a semiconductive LixCoO2 phase has been identified as responsible for the loss of efficiency of the conductive material, when lithium ions are present in the electrolyte. (c) 2008 The Electrochemical Society. [DOI: 10.1149/1.2988095] All rights reserved.