The emission from KCl:Bi³⁺ excited in the X absorption band (i.e. between the A and B absorption bands) was measured as a function of temperature. The polarized emission spectrum and the angular dependence of polarization ratio were also investigated. The X-band excitation produces two emission bands peaking at 345 and 395 nm, the centres of which are not the same. The loosely bonded Cl^- ion arising from the substitution of Bi³⁺ ions into the KCl lattice is assumed to be the colour centre for the X-band emission. The definitive assignment of the two emission bands is presented in terms of the relaxed excited states of the perturbed Cl^- ion, in which the Jahn-Teller interaction coupling to the B₁ and B₂ vibronic modes is taken into account.