In the present investigation we have fabricated the cerium dioxide (CeO2) nanoparticles by green route. While preparing the cerium dioxide nanoparticles by co-precipitation method, Neem leaf extract mixed into the precursor of cerium. The synthesized nanoparticles of CeO2 were used for the preparation of thick film sensor by using screen printing strategy. The fabricated CeO2 sensor was characterized by XRD, SEM, EDS and TEM techniques. The structural characteristics investigated by x-ray diffraction technique (XRD). XRD confirms the formation of cubic lattice of CeO2 material. The surface, texture, porosity characteristics were investigated from SEM analysis, while chemical composition of the material was analysed by EDS technique. The transmission electron microscopy (TEM) confirms the formation cubic lattice of the cerium dioxide material. The thickness of the films was calculated from mass difference method, the prepared film sensors belong to thick region. The fabricated material CeO2 sensor was applied as gas sensor to sense the gases such as LPG, petrol vapors (PV), toluene vapors (TV) and CO2. The CeO2 sensor showed excellent gas response for LPG and PV, nearly 93.20 % and 78.23 % gas response. The rapid response and recovery of the prepared sensors was observed at the tested gases. CeO2 material also employed for antibacterial study at several pathogenic organism such as pseudomonas, staphylococcus aureus and salmonella typhae. From antibacterial study it was observed that the material is capable of inhibiting the growth of these pathogenic microbes.