As an alternative to antibiotics, nanoparticles are increasingly being employed to target bacteria. Nanotechnology has the potential to revolutionize the treatment of bacterial infections. Biosynthesis is becoming increasingly popular as a cutting-edge method for producing functionally diverse Nanoparticles with enormous therapeutic potential. Various biological resources have already proven their ability to manufacture Nano-particles with unique properties. They have a diverse and distinct pool of possibly therapeutic secondary metabolites that can reduce metallic ions to Nano-particles. Selenium dioxide Nano-particles were made from Cinnamomum cassia extract (NPs). The created Selenium dioxides were examined using a variety of techniques, including XRD, UV-Vis, and TEM. Two bacteria were used to investigate the anti-bacterial effect.