Electron transfer (ET) reactions represent an elementary chemical process which occurs in a large  variety of molecules, ranging from small ion pairs up to large biological system.      A theoretical study of photo – induced electron transfer between Ruthenium (II) tirs -( 2,2 ï‚¢- bipyrdine ) Ru(bpy)  2 3 and Methyl Viologen MV2+ in a variety of Solvents at room temperature is presented . This study is based on an optical activation by the absorption of light .The Solvent is described by a dielectric continuum model, and  the transferring is represented by a quantum mechanical wave function . In this application, the reorganization energy  , the driving free energy  G , and the activation free energy G  ‡ are calculated with semi classical model . The electronic coupling for the electron transfer DA V reaction is taken from Mulliken –Hush method, and the rate of electron transfer KET in    2 2 3( ) Ru bpy MV system are calculated with a quantum mechanical model.      Our calculation results for the electron transfer in    2 2 3( ) Ru bpy MV system show a good agreement with the experimentally observed results .