Metal nanoparticles grown within the nanostructured matrix of the amphiphilic polymer poly(octadecylsiloxane) (PODS) are investigated here by transmission electron microscopy. Due to its silanol groups and alkyl chain, PODS forms a bilayered nanostructure containing an intercalated layer of water within an aqueous environment. Replacement of water molecules with metal ions within the siloxy bilayers, followed by reduction, results in the formation of metal nanoparticles. The increase in electron density upon nanoparticle formation permits direct visualization of these bilayers, as well as the individual nanoparticles residing within them. These nanoparticles measure about 1-2 nm in diameter and possess a relatively narrow size distribution due presumably to volume availability within the ordered bilayers of PODS.