Abstract A novel efficient synthesis of 3-hetaryl-4, 5, 6, 7-tetrahydrobenzo [b] thiophenes was achieved by the cyclocondensation of ethyl 2-amino-4, 5, 6, 7-tetrahydrobenzo [6] thiophene- 3-carboxylate with selected o-substituted aromatic amines or with alifatic, aromatic and heterocyclic acid hydrazides in the presence of polyphosphoric acid.