A novel electrolyte salt for non-aqueous electrochemical capacitors, cesium carborane, was electrochemically characterized in two organic solvent systems at different concentrations-acetonitrile and a 1:1 mixture of ethylene carbonate and dimethyl carbonate. It was found that Cs+ ion specific adsorption takes place, being dependent on the electrolyte concentration and on the solvent used. Stronger specific adsorption effect with partial charge transfer was observed from the acetonitrile based electrolytes, where the cesium salt has low solubility. (C) 2014 Elsevier Ltd. All rights reserved.