The knowledge of refractory corrosion through steelmaking slags is mainly based on empiric experiences. For a fundamental understanding of refractory wear in dependence of different combinations refractory material/slag a scientific basis is still missing. This work has the aim to provide this knowledge. The methodology comprises the investiagation of refractory corrosion in contact with various steelmaking slags with mineralogical and thermochemical (Fact Sage) methods. The investigated slags and refractory materials come from voestalpine Stahl Linz AG and RHI AG, respectively. The gained results have proven that a combination of analytical and thermochemical tools can provide a more comprehensive understanding of refractory corrosion.