Copper oxide nanoparticles were synthesized by Chemical Precipitation Method using Copper Chloride Dihydrate (CuCl2. 2H2O), Sodium hydroxide (NaOH) as a precipitating agent. The Synthesized Copper Oxide nanoparticles were characterized by X-ray diffraction (XRD), Scanning Electron Microscope (SEM), Energy Dispersive X-ray (EDX) Spectroscopy, Fourier Transform Infrared Spectroscopy (FTIR). The Antibacterial activity of copper Oxide nanoparticles was tested against both gram positive and negative bacteria. In XRD, the crystal size and dislocation density of Copper Oxide nanoparticles were calculated, Element’s purity was determined by EDX spectra. The SEM image confirms the presence of homogeneous spherical distribution of copper oxide nanoparticles. The nanoparticles shows interactions between copper and oxygen atoms were supported by FTIR studies. Copper Oxide nanoparticles have exhibits good antibacterial activity against Klebsiella pneumonia, Escherichia coli,Staphylococcus, and Bacillus cereus.