Co-oligomerizations of 2,6-dilithio-4,4-diisopropyl- or -diphenyl-dithieno[3,2-b:2′,3′-d]siloles, which were prepared in situ via n-butyllithium treatment of 2,6-dibromo-4,4-diisopropyl- or -diphenyl-dithieno[3,2-b:2′,3′-d]siloles (V or VI), with dichlorodiisopropylsilane or dichlorodiphenylsilane yielded the novel oligomers oligo[(4,4-disubstituted-2,6- dithieno[3,2-b:2′,3′-d]silolene)-alt-(disubstituted silylene)]s VII-X as blue-greenish viscous liquids. These oligomers were characterized using several spectroscopic methods, such as ¹H and ¹³C nuclear magnetic resonance spectroscopy and Fourier transform infrared spectroscopy, photophysical properties, and thermal stabilities, along with density functional theory (DFT) calculations. The absorption spectra of VII, VIII, and X, in particular, revealed partial delocalization over the oligomer backbones in comparison with those of the monomers V and VI, which was consistent with the highest occupied molecular orbital-lowest unoccupied molecular orbital energy trends calculated using DFT. VII-X were generally stable up to 150°C, with the less than 4% loss of the original mass.