We report here the synthesis and characterization of 5,5-bis(dodecyloxymethyl)-5,6-dihydro-4H-cyclopenta[c]selenophene (DCPS) and its characterization by single crystal X-ray diffraction technique. In continuation to this, two new solution-processable copolymers PDCPSV and PDCPTV, comprising of DCPS and 5,5-bis(dodecyloxymethyl)-5,6-dihydro-4H-cyclopenta[c]thiophene (DCPT), respectively, in combination with vinylene unit were synthesized, characterized and compared on the basis of their physical, optical and electronic properties. We have successfully introduced vinylene linkage between two consecutive DCPS or DCPT units in the polymer main chain that resulted in low band gap and oxidatively stable polymers. The 3,4-cyclopentane substitution on thiophene and selenophene affords the planarity to the resulting polymers and the question of regioregularity does not arise in the polymer chain in contrast to the 3-alkyl substitution. PDCPSV showed a p-type mobility of 5.6 x 10(-3) cm(2) V-1 s(-1), whereas PDCPTV showed 3.8 x 10(-3) cm(2) V-1 s(-1). The polymers were further characterized by GPC, TGA, DSC, thin-film XRD, and cyclic voltammetry (CV).