Pb^2＋ has a sensitive complex peak in the water/acetylacetone-dithizone system. The voltammetric behavior of Pb(II) facilitated by dithizone (DzH₂) across the water/acetylacetone interface was investigated by cyclic voltammetry. The process was controlled by diffusion and irreversible. Pb^2＋ transferred from water to acetylacetone to form Pb(DzH)₂ with dithizone. Pb^2＋spike potential appeared at －0.3 V and the linear scope was 5×10^－6～0.1 mol•L^－1. The reliable and sensitive method can be developed for the on-line and in situ determination of Pb^2＋ in industrial waste water.

Key words: liquid/liquid interface, cyclic voltammetry, Pb^2＋, dithizone