This book is designed to collect and review research covering the main directions in investigations of aromatic nitroso compounds in recent decades and to present both the academic aspects of this chemistry as well as the open field of its applicability. The book is divided into five chapters. The basic structural properties of nitroso aromatic molecules are described in the first chapter. The second chapter provides an overview of the methods of preparation of aromatic nitroso and polynitroso compounds, including classical synthetic methods and some new preparative approaches. The third part deals with the physicochemical properties of nitroso aromates and azodioxides, their structure, crystallography, quantum chemical calculations, spectroscopy, typical reactions, and especially focuses on the dimerizations in the solid state. The fourth chapter presents organometallic chemistry.