Recently, organic–inorganic composites have received great attention due to combining the advantages of all components. In order to improve the antibacterial activity of inorganic compounds, Zinc oxide (ZnO) nanoparticles modified with chromium containing metal oxide such as Zinc chromite (ZnCr2O4) and conducting Polymer of Polypyrrole (PPy) were synthesized. For this purpose, ZnO was synthesized. Then, ZnO/ZnCr2O4 composite using co-precipitation method was synthesized and finally, the synthesized ZnO/ZnCr2O4 composite was coated by PPy. The synthesized samples were characterized by X-ray Diffraction (XRD), Fourier Transform Infrared (FT-IR), Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Analysis (EDXA). Furthermore, the antibacterial activity of ZnO, ZnO/ZnCr2O4 and PPy/ZnO/ZnCr2O4 samples were determined against Gram-negative bacterum Escherichia coli and Gram-positive bacterial species Staphylococcus aureus. Results showed that PPy/ZnO/ZnCr2O4 composite demonstrate enhanced antibacterial activity in comparison with ZnO and ZnO/ZnCr2O4 samples.