Trace analyses of zinc, cadmium, and lead at a surface-modified thick-film graphite electrode with bismuth nanopowder have been carried out using the square wave anodic stripping voltammetry (SWASV) technique. For strong adhesion of the bismuth nanopowder onto the screen-printed carbon paste electrode, a Nafion solution was added to the bismuth-containing suspension. From the analyses of the zeta potential and the scanning electron microscopy image of the electrode surface, it is suggested that Nafion plays an important role in the homogeneous distribution of bismuth nanoparticles as well as in creating a strong chemical bond between them. To maximize the electrochemical characteristics of the nanobismuth/Nafion electrode, the optimum conditions of SWASV and the nanobismuth labeling amount were suggested. The sensitivity and detection limit of the nanobismuth/Nafion electrode were quantitatively estimated from the analyses of stripping voltammograms. The proposed "mercury-free" carbon strip electrode, modified with bismuth nanopowder, is conveniently usable and directly applicable to a trace metal analysis without predeposition of bismuth and complicated surface polishing steps. (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3413998] All rights reserved.