This course will cover difficult but important fundamental reactions in chemistry and discuss some of the catalysts that Nature has come up with to mediate these transformations with great efficiency. Some of these processes include longdistance electron transfer; storage, transport and delivery of dioxygen; reduction of dioxygen to water; production of hydrogen from water; fixation of carbon dioxide; conversion of methane to methanol; regio-specific and stereo-selective oxidation of organic substrates; photo-oxidation of water to dioxygen; fixation of nitrogen; and controlled reduction of nitrite and sulfite. An understanding of some of these processes can lead to research in green chemistry and contribute to the development of renewable energy. In addition, the lectures will cover some of the physical methods that bio-inorganic chemists employ to characterize the structure and function of these metalloproteins.