<b>Biosynthesis and Characterization of Zinc Oxide Nanoparticles using Onion Bulb Extract</b> The wide application of nanoparticles stimulates the need for synthesizing them but, the conventional methods are usually hazardous and energy consuming. This leads to focus on “green synthesis” of nanoparticles which seems to be easy efficient and ecofriendly approach. In this study, the plant mediated synthesis of zinc oxide nanoparticles ZnO NPs was carried out using bulb extract of Allium cepa as a reducing agent. The optimized nano zinc thus obtained was quantified and characterized using UV Visible spectroscopy, Fourier Transform Infrared Spectroscopy FT IR , X Ray diffraction, Scanning Electron Microscope SEM , EDAX and Zeta potential analyses. Further, the synthesized ZnO NPs were tested for antimicrobial activity. Nanoparticles, zinc oxide, biosynthesis, Allium cepa 36-44 Issue-2 Volume-2 N. Tensingh Baliah | S. Lega Priyatharsini