Abstract: In a supporting electrolyte containing 2×10^-5Mphen, 0.06MHAc-0.14M NaAc and at pH5.1, we obtained an adsorptive complex wave of Lead-phen by Single-Sweep Polarography. It was found that the peak potential of the derivalivc wave is -0.49V (vs.SCE) and limit of detection for lead is 2.5×10^-8M.We determined the composition of the complex which is 1:1 Pb(Ⅱ)-phen and confirmed that the wave is an adsorptive complex wave. The electrode processes may be presented as follow:Pb²⁺+ phen⇔Pb(phen)²⁺ Pb(phen)²⁺⇔Pb(phen)_2d²⁺ Pb(phen)_2d²⁺+2e+ Hg⇔Pb(Hg)+phen