The vibronic intensities of the vibronic origins due to the three odd-parity vibrational modes of the Γ8(2T2g) → Γ8(4A2g) electronic transition of the ReBr2-6ion are calculated using both crystal-field and ligand-polarization vibronic models. The crystal-field calculations is carried out using the closure approximation, and both models employ the double-group formalism. The vibronic intensity distribution is different for the two models, but by using reasonable values of the radial integrals and atomic charges, satisfactory agreement with experiment is achieved.