Core-shell silver (Ag)-polyaniline (PAni) nanocomposites have been synthesized by the in-situ gamma radiation-induced chemical polymerization method. Aqueous solution of aniline, a free-radical oxidant, and/or silver metal salt were irradiated by gamma-rays. Reduction of the silver salt in aqueous aniline leads to the formation of silver nanoparticles which in turn catalyze oxidation of aniline to polyaniline. The resultant Ag-PAni nanocomposites were characterized by using different spectroscopy analyses like X-ray photoelectron, UV-visible, and infrared spectroscopy. The optical absorption bands revealed that the bands at about 400 nm are due to the presence of nanosilver and the blue-shifted peak at similar to 555 nm is due to the presence of metallic silver within the PAni matrix. X-ray diffraction pattern clearly indicates the broad amorphous polymer and the sharp metal peaks. Scanning electron microscopy and transmission electron microscopy of the nanocomposite showed a uniform size distribution with spherical and granular morphology. Thermogravimetric analysis revealed that the composites have a higher degradation temperature than polyaniline alone. (c) 2007 Wiley Periodicals, Inc.