Introduction: The widespread antibacterial activity of nanoparticles of zinc oxide (ZnO-NPs), specifically by using nano-technology to synthesize its nanoparticles, has had considerable attention. Objective: In the present study synthesis of ZnO-NPs by the solvothermal method and its antibacterial efficacy against Pseudomonas sp. has to be studied. Methods: The precursor 0.1M zinc sulfate and reducing agent 0.1M NaOH were used for the synthesis of ZnO-NPs. The synthesized ZnO-NPs were additionally, characterized biochemically using UV-vis Spectroscopy and X-ray diffraction (XRD) analysis. Results: The __ampersandsignlambda;max and band gap was found to be at 329 nm and 3.87 eV respectively. Bacteria found in contact oral cavities forms biofilms which makes them resistant to orthodox antimicrobial agents. Therefore, to overcome this problem, the present work was focused on the alternative approach based on nanomaterials. Antibacterial efficacy of ZnO NPs was performed against Pseudomonas sp. by Methylene blue reduction assay. Significant inhibition was observed (17 mm) at a 100 __ampersandsignmicro;g/mL concentration of ZnO-NPs. Conclusion: Reactive oxygen species (e.g. H2 O2 ) was a critical influence in many events, including the lack of proton motives as well as the harmful absorption of dissolved toxic Zinc ions as a result including cell wall trauma, increased membrane permittivity, excessive uptakes of dissolved ions of Zn, etc. This contributed to mitochondrial weakening, intra-cellular discharge as well as the release of oxidative stress within the expression of genes, that resulted in inhibition of cell proliferation and cell death.