The reaction of several azulenylalkynes having an aryl substituent with elemental sulfur afforded the corresponding azuleno[2,1-b]thiophenes in moderate to good yields. Decarboxylation of an azuleno[2,1-b]thiophene derivative with an ester function was also achieved by treatment with 100% H₃PO₄. The structural features of the azuleno[2,1-b]thiophene derivatives were revealed by X-ray single-crystal analysis. The optical and electrochemical properties of the azuleno[2,1-b]thiophene derivatives were investigated by UV/Vis spectroscopy, voltammetry experiments and theoretical calculations.