At present work cobalt oxide nanoparticle (Co3O4 NPs) were synthesized via simple coprecipitation method using KOH and NH4OH as the reducing agents. The synthesised materials were applied for the removal of methylene blue (cationic) and Phenol Red (anionic) dyes from the water. Comparative study was done to test the efficacy of the synthesized nanomaterials for the dye degradation, antibacterial and antifungal activities. Further the synthesised material was characterised with X-ray diffraction (XRD) analysis, Fourier Transform Infra Spectroscopy (FTIR), Field Emission Scanning Electron Microscopy (FESEM), Raman spectroscopy and UV-vis spectroscopy to check the purity, crystalline size, and shape of the formed NPs. The Co3O4 NPs synthesised using KOH as the reducing agent showed noteworthy antimicrobial properties as compared to that of NH4OH as the reducing agent and sunlight induced photocatalytic activity for environmental remediation.