A series of tetrahydrobenzothiophene was synthesized with an objective to develop novel and potent amtimicrobial agent of synthetic origin. First, N- propylamine and Ethyl cyanoacetate were reacted to yield Propyl cyanoacetamide I. Then, compound (I) was reacted with cyclohexanone to obtain an intermediate, which was processed to 2-amino-3-N- (propylcarboxamido)- 4, 5, 6,7-tetra hydrobenzo (b) thiophene (II) by well known and versatile Gewald reaction. Reaction of compound II with different aromatic aldehyde yielded the title compound IIa-k. The synthesized compound were purified, characterized and evaluated for antimicrobial activity. Most of the compound exhibited moderate to significant activities.