[en] Optical measurements have been taken in the spectral range 360 to 2,500 nm for thin films of red (α) and yellow (β) polymorphic forms SnI₂. Excitonic transitions in both polymorphs are due to allowed indirect and nearby direct ones, with indirect excitation energies of 2.163, 2.275 eV and direct transition energies of 2.365 and 2.451 eV for the α and β polymorphs, respectively. The band gap energies and the calculated refractive index are related to the relative densities of the polymorphs. The optical transitions are interpreted to be due to the cations. (author)