Primary products of single-electron transfer to/from organogermanium compounds (anion radicals and cation radicals issued from reduction and oxidation, respectively) and their chemistry are considered through different approaches to the generation and study of organogermanium ion radicals; the relationship between the data obtained by various methods, including voltammetry, UV-Vis and photoelectron spectroscopy, and the possibilities of modern computational methods in this field are discussed. The chapter provides a systematized overview of literature data on the ion radicals of tetravalent organogermanium compounds, including germanium catenates, low-valent (germylenes, digermenes, phosphagermene) and hypercoordinated germanium derivatives, including germatranes. General aspects of the ion radical chemistry of organogermanium compounds, as well as its premise for the actively developing area of germylene catalysis in organic and organoelement synthesis are considered along with the possible prospects for the development of this field. © 2023 John Wiley and Sons, Inc. All rights reserved.