Development of methodology directed toward environmentally benign molecular transformations is one of the most important subjects in modern synthetic organic chemistry. As a promising method for environmentally benign transformation of organic molecules, we have focused on the transition metal catalyzed Hydrogen Transfer Reactions. Here, we report our recent studies on hydrogen transfer reactions catalyzed by group 9 metal complexes bearing Cp*(η5-pentamethyl-cyclopentadienyl) ligand and their application to organic synthesis, which include (1) Cp*Ir complex-catalyzed oxidation of alcohols, (2) Cp Ir complex-catalyzed transfer hydrogenation of nitrogen heteroaromatics using 2-propanol as a hydrogen donor, (3) Cp Ir complex-catalyzed carbon-nitrogen and carbon-carbon bond formation using alcohols as alkylating reagents, (4) Cp Ir and Cp Rh complex-catalyzed synthesis of nitrogen heterocycles by intra- and intermolecular carbon-nitrogen bond formation.