The electrochemical behavior of Fe(III)/Fe(II), FeCp2 +/FeCp2, FeCl4-/ FeCl 42- FeBr4-/FeBr4 2- and Fe(CN)63-/Fe(CN)6 4- couples in 1-n-butyl-1-methylpyrrolidinium bis(trifluoromethansulfone) imide (BMPTFSI) room-temperature molten salt was studied by means of cyclic voltammetry. The electrode reaction of Fe(III)/Fe(II) on a platinum electrode was quasi-reversible due to the slow electron transfer while those of other iron complex couples were reversible. The slow electron transfer of the Fe(III)/Fe(II) couple may be related to the strong interaction of the Fe(III)/Fe(II) redox center with surrounding bulky TFS- anions. Each iron complex couple showed its own redox potential, indicating the ligands of Cp-, C-1, Br- and CN- are not replaced with TFSI- having a small donor number. The electrochemical behavior of Fe(CN)63TFe(CN) 64- couples was also investigated in several molten salts which had different organic cations. The redox potential seems to be affected by the acceptor property of the organic cation.