<jats:title>Abstract</jats:title> <jats:p> The structure and stereochemistry of the siderophore isolated from the culture medium of Ralstonia eutropha (formerly Alcaligenes eutrophus) could be elucidated as staphyloferrin B by spectroscopic methods and chemical degradation. The relationship of the three species of the new genus Ralstonia is reflected in the observation that all three form citrate sidero-phores.