Organotin compounds have a very wide range of industrial applications, although R SnX species can be toxic to some forms of life. Consequently, it is important to demonstrate that R3SnX compounds will not accumulate in the environment, but will degrade to non-toxic inorganic forms of tin. Chapter 1, therefore, reviews the toxicological properties and industrial applications of organotin compounds. The spectroscopic techniques used in the titled studies, mainly N.M.R., are also described. The methods by which degradation of an organotin compound may occur are discussed in Chapter 2, and the U.V. breakdown of the methyltin and butyltin chlorides, where R = Me or Bu and n = 1-3, and the U.V. breakdown of the trimethyltin cation, {Me Sn(H 0)2}+, in water are demonstrated. The presence of the hydrated tributyltin cation, {BUgSn(H20), in an aqueous solution of tributyltin ethanesulphonate, Bu SnO SEt, and the various hydrated monomethyltin species inaqueous solutions of methyltin trichloride are also established. Chapter 3 reviews spectrofluorescent methods for determining inorganic and organic tin compounds at sub-p.p.m. levels. Fluorescent methods for determining the concentration of tri-phenyltin species and the total organotin species present in water are developed. A series of new organotin derivatives of the fluorescent reagent, 3-hydroxyflavone, is prepared and their structures in the solid state and in solution are described.