Abstract:A Zn(Ⅱ) modified Pt-electrode was prepared. A new method using oscillo-potentiometry for the titration of Zn(Ⅱ) was described. In 1.0 mol/L hexamethylene tetramine solution (pH 5.5), Zn(Ⅱ) was titrated with EDTA, and two modified Pt-electrodes were used as bi-indicator electrode. The end point of titration was determined by by the observation of an abrupt maximum displacement of the fluorescence spot on the screen of the cathodic oscillograph. When Zn(Ⅱ) content was in the range of 3.0×10-4～2.0×10-3 mol/L, the recovery was in the range of 99.9%～100.2%. Furthermore, the modified electrode showed excellent stability and reproducibility. In 1.0×10-3 mol/L Zn(Ⅱ) solution, the values of end point potentials obtained from 11 continuous determinations were all around 10.1 mV, and the relative standard deviation (RSD) was 0.5%. Moreover, the proposed method has been used in the determination of Zn(Ⅱ) contained in samples and the results are in accordance with that obtained by indicator method.