The subproject “Development of a MIC-cell sealing” is part of the collaborative FERMI project of different partners from industry (Hexis) and universities (ZHAW IMPE and ICP, FHNW). The project is supported by founding from Swiss federal office of energy SFOE.The laboratory of ceramic materials develops glass ceramic based sealings for the separation of reaction zones in between a SOFC high temperature solid oxide fuel cell. Besides the separation effect, the sealing should suppress unwanted reactions between cathode and ceramic zirconia electrolyte. Such reactions lead to a transformation zone where new compounds are formed. Additionally, such reactions impede the use of thinner electrolytes with lower electrical resistivities. The reaction between the metallic interconnector as additional sealing interface partner with some compounds of the glass ceramics furthermore influences the integrity of the sealing.