2,3-Dihydrothiazolo[2,3- b ]thiazolium iodides and bromide were obtained for the first time by the cyclization of corresponding metallyl- and propinylsulfanyl derivatives of 1,3-thiazole with iodine and bromine in dichloromethane without heating and the use of strong acids. The structure of the obtained compounds was studied by 1H, 13C{1H} NMR spectroscopy. Structure of the 3-iodomethyl-3,5-dimethyl-2,3-dihydrothiazolo[2,3- b ][1,3]thiazolium heterocyclic system is characterized by the X-ray analysis. The bonding in the heterocyclic system and non-covalent cation-anion interactions are analyzed on the basis of quantum chemical calculations with periodic boundary conditions; I···S chalcogen bond is discussed.