A new benzimidazole unit, 4'-(tert-butyl)spiro[benzo[d]imidazole-2,1'-cyclohexane] was synthesized and coupled with different donor units like 3-hexylthiophene and 3,4-ethylenedioxythiophene (EDOT) via Stille coupling. The donor-acceptor-donor (D-A-D) type monomers, 4'-(tert-butyl)-4,7-bis(4-hexylthiophen-2-yl)spiro[benzo[d]imidazole-2,1'-cyclohexane] (BIHT) and 4'-(tert-butyl)-4,7-bis(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)spiro[benzo[d]imidazole-2,1'-cyclohexane] (BIED) were electrochemically polymerized, their electrochemical and optical properties were investigated by cyclic voltammetry, UV-vis-NIR spectroscopy techniques. Effect of donor groups on the optical and electronic properties of polymer was studied. (C) 2012 Elsevier Ltd. All rights reserved.