Novel spherical three-dimensional (3D) dendritic gold@polypyrrole (PPy) nanocomposites were successfully synthesized by reacting pyrrole monomer with chloroauric acid (HAuCl4) through a self-assembly process in the presence of poly(sodium 4-styrenesulfonate) (PSS), which acts as both dopant and surfactant. The formation probability and the size of the dendritic gold@PPy nanocomposites depended on the concentrations of PSS, pyrrole and HAuCl4, and reaction temperature. The dendritic AuNPs@PPy nanocomposites were confirmed by scanning electron microscopy, transmission electron microscopy. X-ray diffraction, and X-ray photoelectron spectroscopy. In addition, the AuNPs@PPy nanocomposites had high electrocatalytic activity toward H2O2, which showed excellent potential application in sensing. Crown Copyright (C) 2011 Published by Elsevier Ltd. All rights reserved.