Thermoreversible physical gels of poly(styrene-b-butadiene-b-styrene) (SBS), formed by the dissolution of the block copolymer in a mid-block-selective solvent (THF), have been studied and characterized with particular attention to their morphology and rheological behavior. The effects of the addition of silver (Ag) nanoparticles to the SBS matrix, on the behavior of the physical gels, were also studied. The external surface of the Ag nanoparticles has been modified by using as surfactant material, dodecanethiol, in order to achieve their confinement in just one block of the SBS block copolymer matrix. The results of this study show that the gel stability is not affected by the presence of Ag nanoparticles. In fact, the micellar domains of the nanocomposite gel based on SBS block copolymer and Ag nanoparticles has been obtained and the physical gel behavior have been confirmed by rheological analysis.