Organic-inorganic composites have also gained much attention owing to their excellent combined properties. For the enhancement of the bacteria-inactivation ability of graphene oxide (GO), poly[5,5-dimethyl-3-(3'-triethoxysilylpropyl)hydantoin] (PSPH) was synthesized and attached onto GO through covalent bond. The synthesized inorganic-organic composites (GO-PSPH) were characterized by FT-IR, XPS, XRD, AFM, SEM, etc. After chlorination treatment by sodium hypochlorite, biocidal efficacies of the chlorinated GO-PSPH (GO-PSPH-Cl) against S. aureus (ATCC 6538) and E. coli O157:H7 (ATCC 43895) were tested. The antibacterial testing results showed that the GO-PSPH-Cl has great antibacterial activity and could completely inactivate 5.5 x 10(6) CFU/mL of S. aureus and 1.2 x 10(8) CFU/mL of E. coli O157:H7 within 30 and 10 min of contact time, respectively.