This book is designed to collect and review the research covering main directions in investigations of aromatic nitroso compounds in last decades, and to present both, the academic aspects of this chemistry, as well as the open field of its applicability. The book is divided in five chapters. The basic structural properties of the nitroso aromatic molecules are described in the first chapter. The second chapter is an overview of the methods of preparations of aromatic nitroso and polynitroso compounds, including classical synthetic methods and some new preparative approaches. The third part deals with the physico-chemical properties of nitroso aromates and azodioxides, its structure, crystallography, quantum chemical calculations, spectroscopy, typical reactions, and especially it is focused on the dimerizations in the solid-state. In the fourth chapter is represented organometallic chemistry of nitroso aromatic molecules and its applications in catalysis. The last part of the book deals with the behavior of this class of compounds in the biological systems, reactions with biomolecules and the use in toxicology.