The absorption spectrum in the visible of [(NH3)(5)Ru(4,4 ' -bipyridine)Ru(NH3)(5)](4+) in water has been studied by extensive multireference configuration interaction calculations. Solvent effects were included by the polarizable continuum model. Size and shape of the cavity surrounding the solute molecule were chosen according to a method that we have previously developed for systems in which solute-solvent hydrogen bonds occur. The dependence of the ground state, as well as that of the first singlet and triplet excited states, has been investigated as a function of the torsion between the two pyridine rings of 4,4 ' -bipyridine. The line shape profile of the metal-to-ligand charge transfer (MLCT) band has thus been obtained. The modifications of the band due to a static electric field have then been studied, and the possible role of the triplet MLCT state in determining the observed Stark spectrum has been investigated.