Hydrothermal technique has been used to create nanocrystalline powders of copper substituted zinc ferrite with general formula Zn1-xCuxFe2O4(x = 0.2, 0.4, 0.6, and 0.8). The synthesised samples are recognised by powder X-ray diffraction, which showed prominent peaks due to its considerable crystalline nature. Crystallite size has been determined, and structural analysis shows their cubic nature and remarkable crystalline. Measurements made with FT-IR in the 4000-400 cm-1 range help to clarify the existence of functional groups. Selected Gram negative (Proteus vulgaris) and Gram positive (Bacillus subtilis) bacterial strains were used to test the nanocrystalline powders' antibacterial properties. The incorporation of Cu into Zn ferrite nanoparticles results in an increase in activity. These materials, which have enhanced structural and antibacterial qualities, can be used in hygiene, medicines, and the textile sector.