ZnS has a wider band gap than other conventional II–VI semiconductors. Fluorine has a smaller atomic radius than both sulfide and zinc. ZnS and fluorine doped ZnS films were produced my means of ultrasonic spray pyrolysis (USP) method by spraying on glass substrates heated up to 340±5 ◦C. XRD and Raman spectroscopy were used to determine the crystalline formation and phase contents of these films and investigated the effect of fluorine having smaller atomic radius on both the structural and optical properties of the ZnS film. In addition to Raman spectroscopy, FTIR spectroscopy was used to detect the vibrations of atoms in the molecule. In the scope of morphological properties, SEM analysis was used and these images showed that the incorporation of fluorine in ZnS lattice caused important effects on the surface morphology and particle size. Optical absorption and reflectance spectra of the films that taken between 200 and 900 nm wavelengths were used to calculate the extinction coefficient, refractive index, dielectric constant and average refractive index values. The optical band gap and Urbach energy values of these films were determined depending on the fluorine incorporation.