The electrochemical properties of novel reaction media, ionic liquid (IL)/supercritical CO2 (scCO(2)) systems, were evaluated and the electrochemical carboxylation of various organohalides in these systems was demonstrated. Voltammetric studies revealed that the CO2 solubility in an IL such as N, N-diethyl-N-methyl-N-(2-methoxyethyl) ammonium bis(trifluoromethanesulfonyl) imide ([DEME] [TFSI]) increased in the presence of scCO(2). The IL/scCO(2) systems were found to be effective for the electrochemical carboxylation of various organohalides. (C) 2015 Elsevier Ltd. All rights reserved.