Abstract The method developed for the synthesis of thiazolo [3, 2-a] pyridinium salts has been extended to the first synthesis of simple thiazolo [3, 2-a] pyrimidinium, thiazolo [3, 2-a]- pyrazinium and thiazolo [2, 3-b] benzo [d] thiazolium salts. No method could be found for the cyclization of 4′-bromo-2-(2-benzoxazolylthio) acetophenone to the thiazolo [2, 3-b]- benzoxazolium system.