In this paper, the optical spectroscopic properties of Co3O4 doped borate glass with chemical composition: 60 B2O3, 30 ZnO, (10-x) Na2O, x Co3O4, (where x= 0 (S0), 0.1 (S1), 0.2 (S2), 0.3 (S3), 0.4 (S4), 0.5 (S5) mol %) were investigated. The glass samples (S0-S5) were prepared by conventional melt quenching technique. The formability of all prepared glass samples was examined by XRD and UV–visible spectroscopy techniques. The amorphous nature of glass structure was confirmed by XRD- technique. Archimedes method was used to measure density and calculate the molar volume of the prepared glass composition. It was observed that the density and molar volume of processed glass samples increased by increasing concentration of Co3O4. The optical spectroscopic characteristics of the obtained borate glass have been carried out over the whole range (190-2500nm) for studying the bandpass glass filter and UV cut-off. Through experimental data it was observed that the optical energy gap decreased from 3.25 to 3.03 eV by increasing doped cobalt oxide contents on borate glass. Furthermore, UV cut-off regions increased by increasing concentration of cobalt oxide. The effect of doping concentration on the optical properties of the prepared glass samples (refractive index, extinction coefficient, permittivity, dielectric constants, electric susceptibility and polarizability) was determined and studied.