Nuclear magnetic resonance spectroscopy (NMR) is a powerful technique for elucidating the metabolism of xenobiotics, as it allows for the least ambiguous assignment of chemical structure when compared to other forms of spectroscopy. In addition, it is a sensitive technique that can reveal the presence of transient species that otherwise would not be detected by utilizing either large-scale batch processes or other forms of spectroscopic analyses. The primary focus of this unit describes the use of NMR to identify metabolites arising from the oxidation of thiodiglycol by equine and human variants of alcohol dehydrogenase (ADH). Given that it is often risky to base metabolism studies on a single form of spectroscopy, a spectrophotometric method is also presented. In addition, incorporation of independent organic syntheses in conjunction with the spectroscopic studies to further solidify structural identification of the ADH metabolites is presented.