Joachim Cuntz (born 28 September 1948 in Mannheim) is a German mathematician, currently a professor at the University of Münster.

Joachim Cuntz has made fundamental contributions to the area of C*-algebras and to the field of noncommutative geometry in the sense of Alain Connes. He initiated the analysis of the structure of simple C*-algebras and introduced new methods and examples, including the Cuntz algebras and the Cuntz semigroup. He was one of the first to apply K-theory to noncommutative operator algebras and contributed to the development of that theory. In collaboration with Daniel Quillen, he developed a new approach to cyclic cohomology and proved the excision property of periodic cyclic theory. In recent years, he has been working mainly on C*-algebras that are related to structures from number theory.^[1][2]

Joachim Cuntz had dozens of PhD students and research assistants, many of which are professors in mathematics today.^[2] Among them are:

• Xin Li (PhD 2010, professor of mathematics at the University of Glasgow)
• Ralf Meyer (PhD 1999, professor of mathematics at the University of Göttingen)
• Andreas Thom (PhD 2003, professor of geometry at the TU Dresden)
• Christian Voigt (PhD 2003, professor of mathematics at the University of Glasgow)
• Moritz Weber (PhD 2011, junior professor of mathematics at Saarland University)
• Wilhelm Winter (PhD 2000, professor of mathematics at the University of Münster)
• Joachim Zacharias (PhD 1996, professor of mathematics at the University of Glasgow)

• 1990 Invited speaker at the International Congress of Mathematicians in Kyoto (Cyclic Cohomology and K-homology).
• Max Planck Research Award (together with G. Kasparov), 1993
• Medal of the Collège de France, 1997
• Gottfried Wilhelm Leibniz Prize of the DFG 1999,
• Honorary doctorate from the University of Copenhagen
• ERC Advanced Investigators Grant, 2010
• Fellow of the American Mathematical Society, 2012^[3]

• Cuntz, Joachim (2004). Cyclic Homology in Non-Commutative Geometry. Berlin, Heidelberg: Springer Berlin Heidelberg. ISBN 978-3-642-07337-3. OCLC 851389519.