A sensitive absorptive wave of leucogen-Cu~(2+)-ethylenediamine system was obtained by using single sweep oscillopolarography. It was based on the reaction of Cu~(2+)-ethylenediamine with hydrolysis product of leucogen in 0.1 mol/L NaOH. The peak potential was at -0.37 V(vs.SCE). The linear relationship between the concentration and the peak height was in the range of 4.0×10~(-7)~6.0×10~(-6) mol/L with the RSD of 1.0% and the detection limit of 1.0×10~(-7) mol/L. The recovery was 97.9%~103%. The method was ...