Cu (II) complexes, were synthesized with newly derived biologically active 1,2,4-triazole Schiff bases. The Schiff bases were synthesized by condensation of 3-substituted-4-amino-5-mercapto-1,2,4-triazole with dibenzoylmethane. The synthesized compounds were characterized using elemental analysis, magnetic moment, thermal analysis and spectral tools (FT-IR, 1HNMR, ESR, and UV–Vis spectroscopy). All the synthesized complexes are nonelectrolytes in N,N-dimethylformamide. The synthesized Schiff bases and their Cu (II) complexes have been screened for antibacterial (Escherichia coli & Staphylococcus aureus) and antifungal (Aspergillus flavus & Candida albicans) activity using a modified Bauer-Kirby method. Interestingly, the synthesized Cu (II) complexes were used as precursors for CuO nanoparticles which were characterized using XRD, HR-TEM, FT-IR and UV–Vis spectroscopy. The photocatalytic activity of the prepared CuO nanoparticles was studied by performing the degradation of methylene blue dye under UV illumination in the presence of H2O2 and the results showed that the maximum percent of the degradation of methylene blue dye (MB) was found 96.18% after 360 min.