The effect of Bi impurity on the optical absorption and roentgeno-, photo-, and thermoluminescence spectra of CdI 2 crystals grown by the Bridgman-Stockbarger method is studied. CdI 2 activation with BiI 3 produces a number of absorption bands related to electronic transitions of Bi 3+ . Bi produces no emission centers in CdI 2 . The 550-to 560-nm luminescence of CdI 2 is due to the radiative recombination of self-trapped anion excitons. The observed changes in spectral distribution and the reduction in light yield upon CdI 2 activation with Bi 3+ are mainly due to the reabsorption of emission from native centers by activator centers. Under x-ray excitation, CdI 2 :Bi 3+ accumulates a small light sum at shallow trap levels related to native defects.