Ruthenium　polypyridine　and　polypyridined-derivative　complexes　are　used　in　dye-sensitized　solar　cell　as　a　light　to　current　conversion　sensitizers,　study　on　the　electronic　absorption　spectroscopy　of　which　are　very　important　for　the　understanding　of　their　photovoltaic　character.　A　theoretical　research　of　UV-Vis　spectrum　on　the　Ru(II)L2[L　=　bis(5′-methyl-2,2′-bipyridine-6-carboxylato)],　a　polypyridined-derivative　mononuclear　ruthenium　complex,　is　presented　here.　Transition　excited　states　of　Ru(II)L2　in　the　gas　phase　have　been　studied　by　the　time-dependent　density　functional　theory　(TD-DFT)　using　a　hybrid　functional,　B3LYP,　as　well　as　the　3-21G*　basis　set.　Two　maximum　absorptions　are　dominated　by　the　metal-to-ligand-charge-transfer　(MLCT)　transitions,　from　Ru　4d　orbitals　to　the　bipyridine　rings　π*.　Taking　account　of　solvent　effect,　the　electronic　absorption　spectrum　of　Ru(II)L2　in　N,N′-dimethyl　formamide　(DMF)　solution　has　also　been　investigated　on　the　basis　of　Polarized　Continuum　Model　(PCM)　in　connection　with　TD-DFT.　Calculation　results　indicate　that　the　two　maximum　MLCT　absorption　peaks　are　blue-shifted　in　DMF　solution　with　respect　to　those　in　the　gas　phase,　which　is　in　agreement　with　the　observed　phenomenon　of　other　ruthenium　polypyridine-type　complexes.　©　2006　Elsevier　B.V.　All　rights　reserved.