In this study, we present a new process of developing silver nanoparticles (AgNPs), using intercalated clay (saponite)/poly acrylamide (PAAm) nanocomposite (NC) hydrogels, via the reduction of silver ions with NaBH4 in aqueous solutions. The –NPs obtained are very stable at room temperature due to the extended coil conformation of the PAAm chain. Size and morphology of AgNPs formed within the silicate layers depended on the surface property of clay minerals, which was confirmed by XRD and TEM measurements. The parameters concerning to the diffusion (D) and swelling (Q) of water for the PAAm/saponite NC hydrogels were estimated. In vitro antibacterial assay showed that pristine saponite could not inhibit the growth of bacteria. However, the saponite/poly PAAm NC hydrogels had strong antibacterial activity, particularly against Gram-positive bacteria. With increasing amount (and the interlayer distance) of the layered silicates in the NC hydrogels, the nanocomposites showed a strong antibacterial effect. POLYM. COMPOS., 38:E16–E23, 2017. © 2016 Society of Plastics Engineers.