A new class of polyconjugated polymers, namely poly(2,5-arylidenecyclopentanone) and poly(2,6-arylidenecyclohexanone) has been obtained by condensation of cyclopentanone or cyclohexanone with terephthalaldehyde using alcoholic potassium hydroxide as a catalyst. Copolymerization of the corresponding monomers was also carried out. To characterize these polymers model compounds were prepared from cyclopentanone or cyclohexanone and benzaldehyde. The structures of the model compounds were elucidated by IR, NMR, and elemental analyses. DSC measurements, thermogravimetric, and X-ray analyses. From the SCF-CI calculations, the 2,5-dibenzylidenecyclopentanone, as a model compound, has the trans form. Furthermore, the charge densities of this model, its anionic and cationic forms, as well as the ionization potential and the electron affinity have been calculated.