The study on the mass spectroscopic behavior of the title compounds is based on AP-measurements, the investigation of deuterated derivatives, and the analysis of chain length effects. It is shown that, among other things, the stable [M-STol]⁺-ions produced by 9 homologs will not enter a cyclization reaction within 10^-5 sec. The reactive [M-STol]⁺-species of S,S′-di-p-tolyl dithioadipate possess an abnormal fragmentation behavior (consecutive lass of CO and H₂O), the details of which are elucidated by employment of ²H-labelled compounds and investigation of S,S′-di-p-tolyl 2,5-dimethyldithioadipate. Obviously, the sulfur of the thiol ester group seems to play a decisive role in this and other decomposition processes.