 He was a visiting professor at Harvard (1996/7), Prague, Florence, Mexico City (Centro de Estudios del IPN), Stanford, Berkeley, Scuola Normale Superiore (Pisa), Rome, Buenos Aires, and at IHES.Kohn's work focuses, among other things, on the use of partial differential operators in the theory of functions of several complex variables and microlocal analysis.He has at least 65 doctoral descendants.