This book provides the comprehensive survey of the advances in Organoselenium and Organosulphur chemistry. Synthetic procedure, coordination chemistry and crystal structures are presented in great detail. In studying the chemistry of organochalcogen compounds, it can be very informative to compare and contrast the properties and reactions of particular structural types as the chalcogen atom is varied. Therefore a concise introduction related to the selenium chemistry followed by sulfur chemistry is presented herein to justify the importance of current title.