Kobayashi held many visiting professorships, taking sabbatical leaves from the IBM Research and Princeton University.

• Visiting assistant professor at System Science Department, UCLA
  (Host: Prof. A.V. Balakrishnan)
  July 1969-March 1970.
• Consultant to ALOHA System Project
  (Hosts: Profs. Franklin F. Kuo and Norman Abramson)
  and Visiting Professor at Information Science Department
  (Host: Prof. W. Wesley Peterson), University of Hawaii
  July – December 1975.
• Consulting Professor at Computer Systems Laboratory and Electrical Engineering Department, Stanford University
  (Host: Prof. Michael Flynn)
  January-June 1976.
• Visiting Professor at Technical University of Darmstadt, West Germany
  (Host: Prof. Eberhard Haensler)
  September 1979-August 1980.
• International Professor of Computer Science at the Free University of Brussels, Belgium
  (Hosts: Guy Louchard and Guy Latouche)
  September-December 1980.
• NEC Chair for Computers & Communications, RCAST (Research Center for Advanced Science and Technology), University of Tokyo
  (Host: the late Prof. Takanori Okoshi)
  September 1991-May 1992.
• Visiting professor, Technical University of Darmstadt
  (Host: Prof. Eberhard Haensler)
  June-July, 1992.
• Visiting Professor, Department of Electrical and Computer Engineering, University of Victoria, B.C., Canada
  (Host: Prof. Vijay Bhargava)
  September 1998-January 1999.