Ionic liquids are molten salts with a melting point under 100°C. They are of growing interest due to their outstanding properties and appear to be good candidates for many electrochemical applications. However, ionic liquids represent a huge category of compounds and an electrochemical reference is needed to be able to make comparison of their behavior. For this purpose, the ferrocene/ferrocenium redox couple is considered as the reference of choice because it has a kinetically facile and rapid process. Moreover, this redox couple usually described as a nearly "solvent independent" formal potential system.1 However, a quick look at the literature shows important discrepancies in the heterogeneous electron-transfer rate constant (k°).1, 2 In this work, we chose to study two ionic liquids (1-butyl-1-methylpyrrolidium bis(trifluoromethanesulfonylimide), C4mpyrTFSI and 1-butyl-3-methyl-midazolium bis(trifluoromethanesulfonylimide), C4mimTFSI) in the temperature range between 20°C to 60°C for which several physicochemical properties (conductivity, density, viscosity) were measured. Then, the electrochemical behavior of ferrocenemethanol was examined by different techniques (linear sweep voltammetry, cyclic voltammetry, electrochemical impedance spectroscopy, chronoamperommetry) in the same temperature range with a gold and carbon microelectrodes of 25 µm and 11 µm of diameter, respectively. Modifying the temperature leads to a variation of the conductivity and viscosity implying a change in the mass transport of the redox species to the electrode but also in the rate constant k°. From the linear sweep voltammetry, the rate constant of the redox reaction of ferrocenemethanol was determined by the analysis of steady-state voltamogram3 and compared to results obtained from impedance spectroscopy. Additionally, the variations of the diffusion coefficient of the reduced species and the rate constant with the temperature were also analysed in term of viscosity of the solvent. Bentley, C. L.; Li, J.; Bond, A. M.; Zhang, J., Mass-Transport and Heterogeneous Electron-Transfer Kinetics Associated with the Ferrocene/Ferrocenium Process in Ionic Liquids. J. Phys. Chem. C 2016, 120 (30), 16516-16525. Siraj, N.; Grampp, G.; Landgraf, S.; Punyain, K., Cyclic Voltammetric Study of Heterogeneous Electron Transfer Rate Constants of Various Organic Compounds in Ionic Liquids: Measurements at Room Temperature. Zeitschrift Fur Physikalische Chemie-International Journal of Research in Physical Chemistry & Chemical Physics 2013, 227 (1), 105-119. Mirkin, M. V.; Bard, A. J., Simple analysis of quasi-reversible steady-state voltammograms. Anal. Chem. 1992, 64 (19), 2293-2302. Figure 1