Abstract: In this paper the influence of (NH₄)₃IrCl₆ and (NH₄)₂JrCl₆ on the ionic conductivity of AgCl (Br. I) emulsion microcrystals during the chemical ripening is studied with the aid of dielectric loss measurement in the range of 10^-3-10^-3M/M AgX.As the amount of iridium salts increases, the dielectric loss peak f_max shifts to lower frequency. When the amount of iridium salts added is up to 10^-3M/M AgX, the dielectric loss absorption peak becomes broader obviously. When the amounts of (NH₄)₃IrCl₆ and (NH₄)JrCl₆ are the same, the similar drops of f_max are observed. A probable mechanism of the phenomena observed is discussed.The addition of iridium salts has a great modifying effect on the ionic conductivity of the emulsion microcrystals during the chemical ripening.