Solid oxide fuel cells (SOFC) convert chemical energy from hydrogen, methane, or other hydrocarbons directly into electrical energy and heat. Advantages are low noise during operation as well as relatively low pollutant emissions. This makes them interesting for stationary applications, eg combined heat and power plants for domestic use and for mobile applications, when there is a demand for integrating auxiliary power units. The high operating temperatures of about 850°C and the simultaneous presence by both, reducing and oxidizing atmospheres place high demands on the components of a SOFC. Due to these requirements, glass‐ceramics are proposed as sealants between interconnector and electrolyte. They provide lower costs and lower weight than commercially used silver solders. Furthermore, they have the following impressive benefits: The sealants are electrical insulating, chemical stable and by careful materials selection and adapted manufacturing processes, they adhere well on steel and on ceramic substrates. In order to characterize the adhesion of glass‐ceramic sealants on steel and on zirconia substrates, layer‐like composites are fabricated by screen‐printing and subsequent sintering in air. ... mehrIt turns out that the formation of crystalline phases at the interface is crucial for the adhesion behavior.