Abstract Luminescence spectra of single crystals of CsI:In + excited in the A(304 nm), B(288 nm), C(268 nm) and D(257 nm) absorption bands have been studied in the temperature range 4.2–300 K. Excitation in the A band at 4.2 K gives rise to the principal emission at 2.22 eV accompanied by a partly-overlapping weak band at 2.49 eV. An additional emission band at about 2.96 eV is observed on excitation in the B, C or D bands. Yet another emission band located at 2.67 eV is excited only in the D band. The relative intensities of the bands are very sensitive to excitation wavelength as well as to temperature. The origin of all these bands is assigned in terms of a model for the relaxed excited states (RES). All the luminescence spectra were resolved into an appropriate number of skew-Gaussian components. Moments analysis leads to a value of (1.35 ± 0.02) × 10 13 rad s -1 for the effective frequency (ω eff) of lattice vibrations coupled to the RES. At the lowest temperature, the radiative decay times of each of the intracenter emission bands (2.22, 2.49 and 2.96 eV) show a slow decay ( ∼ 10–100 μs) and a fast decay ( ∼ 10–100 ns). The 2.96 eV band, which is assigned to an emission process which is the inverse of the D-band absorption, exhibits a single decay mode ( ∼ 10 μs). The intrinsic radiative decay rates ( k 1, k 2), the one-phonon transition rate ( K) and the second-order spin-orbit splitting (D) for the RES responsible for the principal emission are: k 1 = (6.0±-0.3)×10 3 s -1, k 2 = (1.33±-0.06)×10 5 s -1, K = (2.4±-0.4)×10 7 s -1 and D = (13.8±-0.5) cm -1.