John Cahn, Emeritus Senior Fellow of the National Institute of Standards and Technology and affiliate professor at the University of Washington, received the 2011 Kyoto Prize in the category of advanced technology. He was cited for “outstanding contribution to alloy materials engineering by the establishment of spinodal decomposition theory.” Cahn developed the theory of spinodal decomposition in alloy materials by in corporating the strain energy term into the free energy of the alloy system. It has made it possible to predict the optimal microstructures of alloy materials and to maximize their functions. The theory has led to the establishment of a design guideline for the development of alloy materials and contributed to the progress of both materials science and the materials industry.