In this paper, MnO2 is added to CaO-SrO-B2O3-SiO2 sealing system to control the redox glass/metal interfacial reaction in Solid Oxide Fuel Cells. The effect of MnO2 dopant on the valance states of Mn ions in glasses, the glass structure and glass/metal interfacial reaction is systematically investigated. The quenched glasses contain Mn2+ ion only; whereas, the Mn3+ content in glasses, held at 600 degrees C for 9 h, increases with increasing MnO2 dopant. The good bondage can be observed at the interfaces between Crofer 22APU and glass containing 6 mol % MnO2, held at 700 degrees C for 500 h. The competitive reaction reduces the redox chromate formation by consuming the oxygen at the glass/metal interface. In addition, the competitive reaction results in the formation of a continuous Mn-Cr oxide scale at the glass/metal interface, which is helpful for reducing the further diffusion of Cr from metallic interconnect to glass. (C) 2014 Elsevier B.V. All rights reserved.