A novel strategy was developed for the in situ incorporation of silver nanoparticles into the supramolecular hydrogel networks, in which colloidally stable silver hydrosols were firstly prepared in the presence of an amphiphilic block copolymer of poly(oxyethylene)-poly(oxypropylene)-poly(oxyethylene) and then mixed with aqueous solution of alpha-cyclodextrin. The analyses from rheology, X-ray diffraction, and scanning electron microscopy confirmed the formation of the supramolecular-structured hydrogels hybridized with silver nanoparticles. In particular, the colloidal stability of the resultant silver hydrosol and its gelation kinetics in the presence of alpha-cyclodextrin as well as the viscoelastic properties of the resultant hybrid hydrogel were investigated under various concentrations of the used block copolymer. It was found that the used block copolymer could act not only as the effective reducing and stabilizing agents for the preparation of the silver hydrosol but also as the effective guest molecule for the supramolecular self-assembly with alpha-cyclodextrin. In addition, the effects of silver nanoparticles on the gelation process and the hydrogel strength were also studied. Such a hybrid hydrogel material could show a good catalytic activity for the reduction of methylene blue dye by sodium borohydride. (C) 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 740-749, 2009