The pure and Li doped MgO nanoparticles were synthesized by co-precipitation method using magnesium nitrate hexahydrate, lithium nitrate and sodium hydroxide as starting materials. The synthesized samples were characterized by various analytical techniques include different technique. The XRD studies confirmed the cubic structures with high purity and the crystallite size is within the range of 10 nm to 13µm. FESEM investigation revealed that the surface morphology of MgO nanoparticles is significantly modified by Li doping. EDX spectra confirmed the presence of the elements Mg, O and dopant Li. FTIR analysis confirmed the presence of Mg-O stretching in the sample. Finally, the antibacterial effect of doped MgO nanoparticles evaluated against pathogenic bacteria by agar diffusion method showed that the nanoparticles have reasonable antibacterial activity against both gram positive (S.aureus) and gram negative (E.coli) pathogenic bacterial strains and retains potential application in pharmaceutical and biomedical industries.