Herein an in situ growth of clean palladium nanoparticles (Pd NPs) on functional reduced graphene oxide (RGO)-coated polystyrene (PS) microspheres is achieved by a simple two-step process. On the basis of the hydrophobic interaction and pi-electron interaction, the PS/RGO composite particles are first prepared by the reduction of graphene oxide in the presence of PS miorospheres. Second, without using any additional reducing agent or-stabilizer, the clean Pd NPs grow in situ on the surface of PS/RGO composite particlesin water through a spontaneous redox reaction between Pd2+ and RGO. Significantly, owing to the stabilizer-free surface of Pd NPs and the synergistic effect of RGO and Pd NPs, the resultant PS/RGO@Pd composite particles feature pronounced catalytic activity toward the reduction of p-rutrophenol and Suzuki coupling reactions. Moreover, the catalyst particles can be easily recovered by centrifugation because of the large size of support microspheres and recycled consecutively.