Silver-polyphenylsilane nanocomposites have been effectively prepared by the dehydrocoupling reaction of phenylsilane (PS, PhSiH3) to polyphenylsilane (PPS, [PhSiH]n) in the presence of silver nitrate. The one-step reduction of Ag(+1) nitrate to stable Ag(0) nanoparticles is mediated by PS, resulting in the formation of Ag-PPS composites. The Ag-PPS nanocomposites were characterized by various analytical techniques such as XRD, TEM, FE-SEM, and solid-state UV-vis. TEM and FE-SEM data clearly show that the silver nanoparticles with the size of < 20 nm are well dispersed throughout the PPS matrix in the nanocomposites. XRD patterns are consistent with those for fcc crystalline silver. The size of silver nanoparticles increased with increasing the relative molar concentration of silver salts added. It was found that in the absence of PS, most of the silver nanoparticles undergo macroscopic precipitation by aggregation, indicating that PPS is essential to stabilize the silver nanoparticles by the complexation of Si-H to the silver metal centers.