In this study, the effects of temperature on the absorption and emission spectra of polyvinyl chloride films were investigated in the presence of diethyl phthalate as a quencher. In this paper, diethyl phthalate (DEP) was used as a quencher at different concentrations to study its effect on the behavior of absorption and emission spectra in the wavelength range from 200 to 350 nm. The films have been treated thermally at 25, 40, 50 and 60 o C. The results showed that the absorption spectrum contains two absorption bands for all samples. The first absorption band appeared in the range of 200 to 220 nm. The maximum absorption band was shifted towards red wavelengths depending on the concentration and temperature. The second absorption band appeared from 260 to 300 nm was weak, broad and unaffected by a concentration while showing a simple response to temperature without displacement in the maximum absorption (λmax.). The changes in absorbance as a function of quencher concentration at room temperature (25 o C) are illustrated.