Walter Kohn, 1998 Nobel Laureate for Chemistry, gave a special ICTP/SISSA condensed matter seminar on 22 June. Kohn, who was born in Vienna, Austria, in 1923, became a naturalized US citizen in 1957 after escaping Nazi Germany in the late 1930s and earning university degrees in Canada and the United States in the 1940s. Renowned for his work as a condensed matter theorist, Kohn has made seminal contributions to our understanding of the electronic function of materials. He played a leading role in the development of density functional theory, which has proved an invaluable concept for physicists, chemists and material scientists. Kohn is also founding director of the Institute of Theoretical Physics at the University of California, Santa Barbara, USA. Since 1985, Kohn has visited the Centre seven times.