The absorption spectrum of [(NH3)(5)Ru-(4,4'-bipyridine)](2+) in the visible has been studied by ab initio methods, taking into account solvent effects by means of the polarizable continuum model and performing extensive CI calculations. The dependence of the ground and lowest excited states has been investigated as a function of the torsional angle between the two pyridine rings of bipyridine in vacuo, as well as in nitromethane, water, and dimethylsulfoxide. Including the torsion, the position and profile of the metal-to-ligand charge transfer band has also been computed. The results obtained in water are in good agreement with the only experimental result available, while they an predictive in the two other solvents.