The reaction of 3,3′-dimethy]-2,2′-bithiazolium salts with potassium superoxide afforded new ten-membered ring compounds 1,2,5,8-dithiadiazecin-6,7-diones in moderate yields. Since these compounds were not obtained from the reaction of KOH-O2 or KOH-H2O2, the reaction is revealed to be specific for superoxide.