Recently, Scientists of the Max-Planck-Institute for Chemical Physics of Solids (MPI CPfS) found a new compound in the scientificly interesting group of ruthenates. They report on the single crystal growth of Ba26Ru12O57 enabled with a ScIDre HKZ mirror furnace. The crystal was grown with a speed of 6 mm/h under 16 bar of an Argon/Oxygen atmosphere (with a ratio of 1:6) and a starting material with a Ba to Ru ratio of 2:1. A large evaporation of Rutheniumoxide lead to the final Ba:Ru ratio in this compound and even with other Ba:Ru ratios of 2:1.1 and 2:1.05 the Ruthenium loss couln't be compensated. Only the 2:1 ratio results in the growth of large impurity-free single crystals of Ba26Ru12O57.