A simple and sensitive electroanalytical method is developed for the determination of lead by adsorptive stripping voltammetry (AdSV) in the presence of morin-5′-sulfonic acid (MSA) and sodium dodecyl sulfate (SDS). The Pb-MSA complex accumulates on the surface of a hanging mercury drop electrode (HMDE) and peak current is measured by square wave voltammetry (SWV). The complex is reduced at -0.48 V and peak current increases when low concentrations of SDS are added to the sample solution. The experimental variables pH, MSA concentration (CMSA); accumulation time (tacc); accumulation potential (Eacc), and SDS concentration (CSDS), as well as potential interferences, are investigated. Under the optimized conditions (pH 3.2; CMSA: 0.5 μmol L-1; tacc: 60 s; Eacc: -0.35 V, and CSDS: 20 μmol L-1), peak current is proportional to the concentration of Pb(II) over the 0.1-32.0 μg L-1 range, with a detection limit of 0.04 μg L-1. The relative standard deviation for a solution containing 5.0 μg L-1 of Pb(II) solution was 1.5% for seven successive assays. The method was validated by determining Pb(II) in synthetic sea water (ASTM D665) spiked with ICP multi-element standard solution and in certified reference water (GBW08607). Finally, the method was successfully applied to the determination of Pb(II) in tap water and sea water after UV digestion.