We have developed molecular mechanics parameters for Ru-II-polypyridyl coordination compounds with the MM3* force field in MacroModel. X-ray structures, together with a B3LYP frequency calculation on a model system, have been utilized in the parametrization. The performance of the force field and the quality of each parameter is analyzed. A clear qualitative correlation have been found between coordination geometry and emission propel-ties for the ruthenium polypyridyl complexes examined in this paper.