N-butyl-N-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide (BMPyNTf2) was synthesized and characterized by CHNS elemental analysis, H-1 and C-13 NMR and IR spectroscopy. Europium tris[bis(trifluoromethylsulfonyl)imide] (Eu(NTf2)(3)) Was prepared and studied for the electrochemical behavior of Eu(III) in BMPyNTf2 at glassy carbon and stainless steel working electrodes at 298-373 K by cyclic voltammetry, chronopotentiometry and chronoamperometry. Cyclic voltammogram of Eu(III) in BMPyNTf2 consisted of a quasi-reversible cathodic wave at -0.45V (vs. Fc/Fc(+), 373 K), which could be attributed to the reduction of Eu(III) to Eu(II) and an irreversible wave at -2.79 V (vs. Fc/Fc(+)) due to reduction of Eu(II) to Eu(0). The diffusion coefficient of Eu(III) in BMPyNTf2 was determined to be in the range of similar to 10(-7) cm(2) s(-1) by various electrochemical methods and the charge transfer rate constant was determined to be similar to 10(-5) cm s(-1) by cyclic voltammetry. (C) 2009 Elsevier Ltd. All rights reserved.