This paper presents the results from the investigation of the influence of ion size on the capacitance behaviour of TiC-derived carbon (CDC) powders in the ethyl-methylimmidazolium-bis(trifluoromethanesulfonyl) imide ionic liquid (EMI, TFSI) used as neat electrolyte at 60 degrees C or as salt dissolved in acetonitrile and tested at room temperature. These studies were carried out with the assembly of conventional 3-electrode electrochemical cells as well as using the Cavity-MicroElectrode (CME) technique. The issues regarding the extents of desolvation of the electrolyte ions when adsorbed in the pores of the CDCs under applied potential were studied, the CME technique was found to be particularly efficient in the deduction of the effective ion size under solvated conditions. (C) 2009 Elsevier Ltd. All rights reserved.