Novel ruthenium(II) polypyridyl complexes with diethynylphenanthrolines containing acetylthiophenyl unit(s) have been prepared and characterized by photophysical measurements. These complexes showed the MLCT and the lowest energy pi-pi* absorption bands, and also intensive broad emission bands assignable to a triplet MLCT transition were observed in the deaerated solution. The electrochemistry of these complexes in the solution and on self-assembled monolayers on the gold electrode clearly showed Ru(II)/R(III) redox waves.