In this paper, the electrochemical behavior of Ir3+ ions in melting NaCl-KCl-CsCl-IrCl3 and the major kinetic parameters were investigated by transient and steady electrochemical techniques from 823K to 913K. Effects of the electrochemistry of Ir3+ ions on the microstructure of Ir coatings were also discussed. The electrochemical reduction of Ir3+ ions from the melts was the diffusion-controlled and irreversible reaction with exchange of three electrons at 823–883K and converted to be a quasi-reversible one with the temperature increasing to 913K. The major kinetic parameters of Ir3+/Ir couples, the diffusion coefficient D0 and exchange current density j0, respectively increased from 2.4×10−6cm2/s to 9.2×10−6cm2/s and from 5mA/cm2 to 16mA/cm2 with the temperature. With the temperature and applied cathodic potential decreasing, the microstructure of Ir coatings converted from the coarse and preferential oriented columnar grain structure to the fine and unoriented dispersive grain structure.