John Tse is a scientific leader, nationally and internationally, in the application of sophisticated computational and experimental methods to determine the relation between structure and properties of complex solids. His fundamental work on phase transformations in ice, and on the structure and thermal properties of natural and synthetic gas hydrates (clathrates), is of great potential significance for the eventual exploitation of this immense resource. He has applied computer simulations, synchrotron radiation techniques and neutron scattering with great success to a wide range of subjects including the elucidation of structure, bonding and superconductivity in high pressure solids, and alloys for batteries and aerospace materials.