This article is motivated by ensure the fire safety of the building and deeper understanding on special cements under elevated temperature loads. Knowledge about influence of high temperatures on calcium sulfoaluminate cement (CSA) based materials has crucial impact on ensuring the fire safety of the buildings. CSA based composites are dedicated to special usage in demanding infrastructure constructions. As there is no or insufficient evidence on the influence of heat on calcium sulfoaluminate materials, this article is motivated to extend current literature knowledge on CSA microstructures at higher temperatures up to 800 °C. Recognising the effect of high temperature is particularly important given the significant differences between CSA and Ordinary Portland Cement (OPC). Evidence shows influence of mixture proportion on composite structure, filler-matrix bond, and matrix behaviour during temperature exposure. Obtained results might help in understanding phenomena occurring within material under temperature load and determine next research directions in this area.