The research on hybrid materials composed of inorganic and organic species in the nanometer range is motivated by the synergic combination of their native properties in a unique material. In this paper, we report a new one-pot synthesis of a ternary nanocomposite based on a conducting polymer (polyaniline – PANI) and silver, using mesoporous silica (MCM-41) as a hard template to promote the controlled growth of both polymer chains and silver nanoparticles. The presence of these reaction products was proved by the appearance of the characteristic diffraction peaks of face-centered cubic metallic silver phase in the X-ray diffractogram and by the presence of typical bands of polyaniline as emeraldine salt in the FTIR and UV-Vis spectra. The preservation of the ordered MCM-41 mesostructure after the polymerization reaction was also attested by XRD and TEM analysis and it was accompanied by a decreasing of the particle size as observed in the SEM images. N₂ adsorption–desorption isotherms support the statement that PANI chains and AgNP have been incorporated mainly into the channel of MCM-41, a fact also attested by TEM images. The electrical conductivity of this nanocomposite is on the order of 10⁻³ S cm⁻¹, which is one million times higher than the value obtained for a MCM-41/polyaniline composite. Although some reports about the isolated incorporation of polyaniline or silver nanoparticles into the MCM-41 pores are found in the literature, to our knowledge this is the first time that such nanocomposite preparation is reported.