Rudolph Marcus, born in 1923 in Toronto, Canada, graduated in chemistry and received his Ph.D. from McGill University in Quebec. He developed a theory on the transfer of electrons between molecules and how this process impacted on the energy of the molecular system. The mathematical expressions he formulated apply to such different electron transfer reactions as the fixation of light energy by green plants, the photochemical production of fuel or the conductivity of polymers. “For his contributions to the theory of electron transfer reactions in chemical systems” Professor Rudolph Marcus was awarded the Nobel Prize in Chemistry in 1992. As Arthur Amos Noyes Professor of Chemistry at the California Institute of Technology in Pasadena he is continuing his studies on the theories of chemical reactions and intramolecular dynamics.