In our group, the fundamental utilization and application of catalysis are studied due to the solution of environment and the energy problems, as well as various kinds of chemical industry processes. It is aimed for the developments of the selective oxidation or reduction catalyst and the investigations of photocatalyst using clean photo-energy in terms of resource and energy saving. The reaction mechanism and behavior of reactants over the catalyst surface are observed by the electron microscope, various spectroscopic analysis and the isotope measurements. We also investigate about the formation of hydrogen from water over photocatalysts under a light irradiation. A clean system of the generation of electrical energy at each home may realize in the near future, if successful.