Polyaniline/gold nanoparticles (PANI/AuNPs) nanocomposites were prepared using a simple self-assembly procedure. Polyvinyl pyrrolidone (PVP) was used as a stabilizing ligand of AuNPs and was shown to prevent the aggregation of AuNPs and to improve the affinity of AuNPs to PANI. By varying the ratio of PANI to AuNPs, the amount of loaded AuNPs was effectively controlled. UV-vis spectroscopy, transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and electrochemical methods were used to characterize the nanocomposites. The nanocomposites showed electroactivity in neutral solution, making them promising candidates for various bioanalytical applications. A sensor constructed using PANI/AuNPs nanocomposites showed 6-fold higher electrocatalytic activity toward the oxidation of ascorbic acid than that composed of a pure PANI-modified electrode. (C) 2010 Elsevier Ltd. All rights reserved.