The four mercaptans studied were 2-mercaptopyridine (2MP), 2-mercaptopyridine-N-oxide (2MP-0), 2-mercaptopyrimidine (2MPr), and 2-mercapto-4-methylpyrimidine.HCl (2MmPr). The pKg values of each compound were determined by both an ultraviolet spectroscopic method and a polarographic method. The pKa values calculated by each technique were in good agreement. The reversibilty of each compound's electrode reaction was assessed from their sampled direct current (DC) polarograms, and it was found that each reaction was quasireversible in nature. The electrocapillary (EC) curves of 2MP and 2MP-0 indicated that the product of their corresponding electrode reactions (a mercury thiolate salt) was adsorbed at the electrode surface. In cyclic voltammetric (CV) analysis, the oxidation peak current was controlled by diffusion of the mercaptan to the electrode. However, as the concentration was increased, an adsorption controlled oxidation peak was also present in the recorded CV's. The CV's displayed the characteristics of weak thiolate adsorption at the electrode surface, and also the film formation was dependent on the time the potential was held positive of the reaction potential. Calibration curves from differential pulse (DP) polarograms and differential pulse cathodic stripping voltammograms (DPCSV) were constructed to find the linear dependence of peak current with concentration. The limit of detection for each mercaptan using DPP was 1x 10-5M, and lxlO”'M using DPCSV. Differentiation of the mercaptans in mixtures was also investigated. The peak current due to 2MP, at concentrations higher than 1x10 M, was greater than that due to equimolar concentrations of the other three mercaptans. This seemed to indicate that the 2MP electrode reaction product was adsorbed in a more compact film at the electrode surface, than the products of the other three mercaptans. The different possible electrode mechanisms and their correlation with their current potential equations were examined. A voltammetric procedure was then developed for the determination of 2-chloropyridine-N-oxide (2PC1-0) and the sodium salt of 2MP-0 in an industrial process stream.