The electrochemical behavior of iodide ions has been studied in the ternary fluoride salt, LiF-NaF-KF and in the binary salts, LiF-CaF2 and LiF-ThF4. The electrochemical study demonstrated that iodide ions are oxidized to produce gaseous species in the three molten fluoride salts. However, the stability of iodide ions was observed to be influenced by the fluroacidity of the molten salt. The efficiency of the extraction of iodide ions was examined in LiF-NaF-KF and LiF-ThF4. UV-visible spectroscopy was used to quantify the amount of iodide ions oxidized after the execution of several coulometries at applied potential, these coulometries simulated the fluorination step in the reprocessing unit designed for the MSFR. The efficiency of extraction determined in LiF-ThF4 is higher than 95 % while it is close to 64 % in LiF-NaF-KF at 650°C