Abstract: It was found tbat when THAQ was pretreated with NaNO₂ in acid solution, a sharp,symmetric and sensitive peak current of Zr(Ⅳ)-THAQ complex in borate buffer solution was produced at -0.81V(vs.SCE).The height of the peak of the complex was in direct proportion to the concentration of zirconium in the range of 2.0×10^-7 to 5.5×10^-6M. The limit of the determination was 20 ppb of Zr(Ⅳ).A new oscillographic method for the determination of micro amount of Zr(0.0005%) in steel and alloys has been then developed.The method was simple to operate,nontoxic and the results of the analysis were satisfactory accurate.The composition ratio of Zr(Ⅳ) to THAQ in complexes determined was 1:2 and 1:4.The stability constants of the correspoding complexes calculated as β₁= 7.1×10¹⁰ and β₂=8.9×10²¹. The results showed that the peak current of Zr(Ⅳ)-THAQ is of adsoiption character.