Electroactive ionic liquids obtained by modifying imidazolium with ferrocenyl moiety and alkyl chains of different lengths (n = 1, 4, 8 and 12) were studied in their pure form and dissolved in ethylene/diethylene carbonates (EC/DEC) solvent. Bis(trifluoromethanesulfonyl)imide (TFSI) was used as the anion. The conductivity of the pure ionic liquids (0.1 to 0.04 mS . cm(-1)) was found to decrease with the increase in alkyl chain length as expected from larger van der Waals interactions. The conductivities of carbonate solutions of redox ionic liquid (50% vol.) were less affected by the chain length but were strongly dependent on the presence of Li ions due to their coordination with TFSI, providing viscous solutions (86-111 cP) which decreased the self-diffusion of the redox imidazolium by a factor of 6. The equilibrium potential of the RIL dissolved in the carbonate solvent was not affected by the alkyl chain length, but mass transport by migration caused a distortion in cyclic voltammograms for highly concentrated solutions. (C) 2014 The Electrochemical Society.