Effect of temperature on the optical absorption spectra and optical parameters is investigated in new synthesized polyester films of poly [oxyiso-phthaloyloxy (2-methoxy-p-phenylene) methylidyne (2-oxo-1, 3-cyclohexanediylidyne) methylidyne (3-methoxy-p-phenylene)](I) and poly [oxysebacoyloxy-(2-methoxy-p-phenylene) methylidene (2-oxo-1, 3-cyclohexanediylidene)-methy-lidene-(3-methoxy-p-phenylene)](II). Absorption measurements are carried out in the temperature range 80–370 K and in the photon energy range 1.9–4 eV. The optical absorption spectra of polymers I and II reveal excitonic absorption bands at 80 and 120 K respectively. These bands are associated with n→ π∗ optical transitions along polymer backbone chains. Analysis of optical absorption data indicates that the Tauc equation for indirect optical transitions successfully explains the optical absorption process in polymeric film I, whereas …