In this research study, the magnesium oxide nanoparticles were synthesized using an inexpensive and simple hydrothermal method. A pure magnesium metal powder, de-ionized water, and hydrogen peroxide (H2O2) was utilized as the starting materials. The synthesized MgO was dense, uniformly distributed with a relatively spherical shape, without any cracks and voids as confirmed by the scaning electron microscopy (SEM) analysis. The structure was crystalline with a high purity. No other peak corresponding to any other material or metal could be ascertained from powder X-ray diffraction (XRD) pattern. The crystallite size of the prepared samples was found to be nearly 18 nm which was favorable for antibacterial activity. The antibacterial activity of MgO nanostructures was carried out by using disc diffusion method. The inhibition zones of diameters = 1 mm were observed in case of salmonella and Staphylococcus aureus, however, in case of E. Coli inhibition zones of diameter = 2 mm was obtained.