This work represents a green synthesis of Lanthanum and Cerium oxide nanoparticles (NPs) using Azadirachta Indica (Neem) leaf extract. La2O3 and CeO2 NPs were characterized for purity and structural properties using different techniques such as Ultra Violet-Visible (UV-Visible), Fourier Transform Infra-red (FTIR), X-ray Diffraction (XRD) and Brunauer–Emmett–Teller (BET) analysis. Scanning Electron Microscopy (SEM) and high-resolution Transmission Electron Microscopy (HRTEM) reveal a spherical shape having an average size of 10-50 nm. BET analysis shows an increment of surface area from 14.909 m2/g to 42.144 m2/g. The peak pore volume of metal oxide nanoparticles increases from 0.181 cm3/g to 0.2338 cm3/g. Further, synthesized NPs were analyzed for dielectric behaviour, antibacterial studies, and hemolysis assay.