Abstract: To investigate the mechanism and influence of oxide and niobium metal on the electrodeposition of niobium, the electrochemical reaction mechanisms of niobium ions in LiF-NaF-KF eutectic (FLINAK) melt at 973 K was studied by chronopotentiometry, chronoamperometry and cyclic voltammetry. The electrochemical reduction process of Nb(V) (K₂NbF₇) in FLINAK melt relates to the complex anions. A two-step electrochemical reduction with disproportionate and catalytic reactions is proposed. The metallic niobium in K₂NbF₇-FLINAK melt can reduce the catalytic reaction. The influence of oxide (Na₂O) on the electrochemical processes of Nb(V) in K₂NbF₇-FLINAK-O^2- melts without and with niobium metal present was also studied. When oxide present in K₂NbF₇-FLINAK melt, a much stable oxyfluorocomplex ion is formed. Cyclic voltammetry showed that the reduction potential of oxyfluoro-complex ion is more negative than that of fluorocomplex ion (NbF_62-). The electrochemical stability of NbOF_63- is higher than those of NbF_72- and NbF_62-. An optimum composition for a coherent niobium metal coating on low-carbon steel is found to be 2.7%K₂NbF₇-0.5～2.0%Na₂O-FLINAK in molar fraction. The cathodic current density is about 90 mA/cm².