In this work we report for the first time differential capacitance curves measured at imidazolium dicationic ionic liquid/electrode interfaces as a new strategy to understand the interfacial behaviour of ionic liquids (IL) near a charged electrode. The ionic liquid studied (1,5-bis(3-dimethylimidazolium)pentane di-bis(trifluoromethylsulfonyl)imide [C-5(MIM)(2)][Tf2N](2)) contains a cation with two positively charged imidazolium rings substituted with a methyl group connected by a pentane linkage alkyl chain length providing a new cationic structure variation. The comparison with the analogue monocationic ionic liquids showed that the dicationic liquid has a wider electrochemical polarization window and a more positive potential of zero charge at a Hg electrode. Differential capacity curves measured at dicationic ionic liquid/Hg interface show similar shape compared with analogous monocationic ionic liquids and revealed to be very sensitive to the electrode material. (C) 2013 Elsevier Ltd. All rights reserved.