Despite a renewed interest in Ge as a competitor with Si for a broad range of electronic applications, the microstructure and the electronic properties of the dangling bonds that, in analogy with Si, are expected at the Ge/oxide interface have escaped a firm spectroscopy observation and characterization. Clear evidence based on contactless electrically detected magnetic resonance spectroscopy of a dangling bond at the Ge (111)/GeO 2 interface is reported in this Letter. This result supports the similarity between dangling bonds at the Si (111)/oxide and Ge (111)/oxide interfaces, both showing C 3 v trigonal point symmetry with the main axis oriented along the⟨ 111⟩ direction. In contrast, at the Ge (001)/oxide interface the absence of the trigonal center in favor of a lower symmetry dangling bond marks the difference with the Si (001)/oxide interface, where both centers are present and the one having higher point …