Since the quality demands for casted steel products rose over the last decades, harmful impurities, such as solid, non-metallic inclusions, have to be removed already during the steelmaking process. While larger, exogenous inclusions are disposed by slag or casting systems, the removal of endogenous inclusions poses a greater challenge due to their small size. For this reason, new filtration concepts on the basis of carbon-bonded alumina filters have been developed within the framework of the Collaborative Research Center CRC 920 to decrease the number of inclusions. Previous studies evinced that the application of an additional functional coating on these filters increases noticeably the filtration efficiency. In order to investigate the impact of spinel compounds as functional coating material for the steel melt filtration, five different spinels (FeAl2O4, MgAl2O4, MnAl2O4, Fe0.5Mg0.5Al2O4, and Fe0.5Mn0.5Al2O4) in combination with carbon were applied on carbon-bonded alumina filters and sintered at 1400 °C under reducing atmosphere, whereby the majority of the spinel compounds decomposed partially. Afterwards, the coated filters were immersed in a 42CrMo4 steel melt at 1650 °C for 10 seconds. The examination of the resulting microstructure revealed that multicrystalline structures, mainly consisting of alumina, were formed on the filter surface and distinguished significantly in their build-up, depending on the coating material used. In connection with the steel cleanliness analysis, the results indicated that alumina inclusions were also involved in the formation process, leading to a considerable decrease of alumina particles in the steel melt. The highest potential for the steel melt filtration was achieved with the Fe0.5Mn0.5Al2O4-C coated filter, which obtained a reduction of about 60 % alumina inclusions after filtration.