Roger Powell is a world leader in the field of metamorphic geology, particularly in the application of thermodynamics to predicting mineral assemblages and phase relationships in natural rocks. He has pioneered the development of quantitative approaches to the study of metamorphism and rigorously understanding the physical conditions under which metamorphic reactions occur. The work of Professor Powell, his research group and his network of international collaborators has established Australia clearly at the forefront of work in this field. In 2004 he was honoured as an ISI Citation Laureate for being the most highly-cited Geoscientist in Australia.