Ag/graphene nanocomposites have been demonstrated to be promising catalysts for hydrogenation reduction of p-nitrophenol (p-NP) to p-aminophenol (p-AP). Herein, we reported the synthesis of graphene-supported silver nanoparticles (Ag/G) using one-step and stabilizer-free process. The obtained Ag/G nanocomposites were demonstrated to be efficient catalysts for the reduction of p-NP to p-AP. The reaction kinetics of the catalytic reduction, including the effects of catalyst concentrations and temperatures are reported. These results are of significant values for the scale-up of using Ag/graphene catalysts for hydrogenation reduction.