Abstract: A new construction of the aurocyanide ion-selective electrode has been made. A PVCsensing membrane has been consisted of the aurocyanide salt of the trioctylhexade-cylammonium as the ion-exchanger. The platinum electrode immersed in a 0.01M KAu(CN)₂-0.01M K₃Fe(CN)₆-0.01M K₄Fe(CN)₆ solution has been tested as the internal reference electrode system. The basic characteristics of the electode are studied. At 25℃, the electrode shows Nernstian response for aurocyanide ion over the concentration range from 1× 10^-1M to 3.2×10^-7 Maurocyanide ion with a slope of 59mV. The detection limit is down to 8×10^-8M. The potential selectivity coefficients for more than ten anions have been measured, and the regularity of the potential selectivity coefficients has been discussed. The results show that the electrode exhibits a good selectivity for the aurocyanide ion. In a preliminary application gold in aurocyanide plating solution has been determined by using the proposed electrode.