Thiophene is a heterocyclic aromatic organic compound. It is a clear colorless lachrymatory liquid with a strong and very unpleasant odor. Thiophene is often found naturally occurring in petroleum in concentrations up to several percent.

Thiophene is aromatic because one of the two electron pairs of the sulfur atom contributes to the delocalized pi electron system, in a manner analogous to the compound furan.

See also

• Pyrrole, an analog with a nitrogen atom instead of the sulfur atom.
• Furan, an analog with an oxygen instead of the sulfur atom.
• Simple aromatic rings