Fine dispersion of graphenes is crucial for the application of graphenein various fields. However, graphenes are frequently aggregated due to the large surface area and van der Waals interactions between themselves during the mixing process. Thus, various modifications of graphenes are necessary for the fine dispersion. Introduction of functional groups into graphenes accompanies loss of inherent advantages. In this study, introduction of silver nanoparticles into graphenes by in situ process was investigated. Especially, microwave irradiation was employed for the syntheses sincegraphenes absorb microwave efficiently and became heated quickly. Formation of silver nanoparticles on the grapheneafter microwave irradiation was confirmed and the average diameter of the silver nanoparticles in the hybrids was about 30 nm. Rheological and electrical properties of the epoxy resins filled with the hybrids are discussed in this report.