1,3-Dithiolium and 1,3-oxathiolium salts are positively charged 6 electronically conjugated cations containing two hetero atoms in a five-membered ring. They exhibit a high reactivity toward nucleophiles. This study has shown that 1,3-dithiolium cations form an interesting class of compounds because of their non-benzenoid aromaticity and that 1,3-oxathiolium cations are highly versatile synthetic intermediates which can provide a number of novel heterocyclic compounds and their precursors depending on the nature of the nucleophiles and the reaction conditions.