This study investigates Bi2O3-B2O3-BaO-ZnO glass with variations of the Co3O4 content (0.25, 0.5, 1, and 2 wt%) and the interaction between transparent dielectric and Ag electrodes heat-treated at 500-560 oC for 30 min. The glass transition temperature, softening temperature and thermal expansion coefficient were 432 oC, 460 oC and 81.4 × 10-7/ oC, respectively. The transmittance of 0.25 wt% Co3O4 to which dielectric was added was highest and was decreased due to coloration with the addition of more than 0.25 wt%. However, without Co3O4, the transmittance of the transparent layer was decreased due to the formation of Ba5Bi3; however, the occurrence of the crystal phase decreased as a result of the addition of Co3O4. The amount of Co2+ ions increased as the Co3O4 increased. With a maximum of Co3+ ions, the highest transmittance was observed.