This annual review of the literature, the 50th volume in the present series, provides a comprehensive and critical survey of a vast field of study involving organophosphorus compounds, ranging from phosphines, their chalcogenide derivatives and phosphonium salts, phosphorus (III) acid derivatives, phosphorus (V) acids, penta- and hexa-coordinated phosphorus compounds, phosphazenes and related phosphorus-nitrogen bonded compounds. Coverage is also presented of applications of organophosphorus compounds in homogeneous catalysis for synthesis of bulk and fine chemicals and also in applications as reagents in green synthetic procedures.