We report scalar and four component relativistic density functional calculations on octacyanorhenate [Re(CN)(8)](2-) and [Re(CN)(8)](3-) complexes. The relativistic calculations predict that the molecular g-tensor of the paramagnetic [Re(CN)(8)](2-) complex is isotropic. The calculated optical electronic transitions for both complexes with a polarizable continuum model using a time dependent density functional (TDDFT)/B3LYP formalism suggest that the [Re(CN)(8)](3-) complex may distort towards dodecahedral geometry in solution. The electronic excitations of LMCT type of [Re(CN)(8)](2-) are displaced at very high wavelengths with significant oscillator strength values which is characteristic of Re compounds having luminescent behaviour. Thus, our calculations predict that [Re(CN)(8)](2-) could be luminescent. (c) 2006 Elsevier B.V. All rights reserved.