Two symmetrical diacetylene monomers containing thienyl moiety as the side groups, namely 1,4-bis(2＇-thienyl)butadiyne and 1,4-bis(3＇-thienyl)butadiyne, are reported which have been successfully polymerised electrochemically. They have also been polymerised chemically in solution using Lewis acid as initiator. The resulting polymers have been characterised by elemental analysis, infrared spectra, absorption spectra and by solid state NMR spectra. The polymers were found to have conjugated pi-electron structure and both of them show high environmental stability. The properties of the polymers have been compared with that of poly(3-methylthiophene) which is a conventional and much studied conjugated polymer. The electrical conductivity of the polymers has also been investigated.