The 47th IChO was held in Baku, Azerbaijan, July 20–29, 2015.

 The 46th IChO was held in Hanoi, Vietnam, July 20–29, 2014.

 The 45th IChO was held in Moscow, Russia, July 15–24, 2013.

 The 44th IChO was held in Washington, D.C., United States, July 21–30, 2012.

 The 43rd IChO was held in Ankara, Turkey, July 9–18, 2011.

 The 42nd IChO was held in Tokyo, Japan, July 19–28, 2010.

 The 41st IChO was held in Cambridge, England, United Kingdom July 18–27, 2009.

 The 40th IChO was held in Budapest, Hungary, July 12–21, 2008.

 The 39th IChO was held in Moscow, Russia, July 15–24, 2007.

 The 38th IChO was held in Gyeongsan, South Korea, July 1–11, 2006.

 The 37th IChO was held in Taipei, Taiwan, July 16–25, 2005.

 The 36th IChO was held in Kiel, Germany, July 18–27, 2004.

 The 35th IChO was held in Athens, Greece, July 5–14, 2003.

 The 34th IChO was held in Groningen, Netherlands, July 5–14, 2002.

 The 33rd IChO was held in Mumbai, India, July 6–15, 2001.

 The 32nd IChO was held in Copenhagen, Denmark, July 2–11, 2000.

 The 31st IChO was held in Bangkok, Thailand, July 4–11, 1999.

 The 30th IChO was held in Melbourne, Australia, July 5–14, 1998.

 The 29th IChO was held in Montreal, Canada July 13–22, 1997.

 The 28th IChO was held in Moscow, Russia, July 14–23, 1996.

 The 27th IChO was held in Beijing, China, July 13–20, 1995.

 The 26th IChO was held in Oslo, Norway, July 3–11, 1994.

​ The 25th IChO was held in Perugia, Italy, July 11–22, 1993.

 The 24th IChO was held in Pittsburgh and Washington, D.C., United States, July 11–22, 1992.

 The 23rd IChO was held in Lodz, Poland, July 7–15, 1991.

 The 22nd IChO was held in Paris, France, July 8–17, 1990.

 The 21st IChO was held in Halle, East Germany, July 2–10, 1989.

 The 20th IChO was held in Espoo, Finland, July 2–9, 1988.

 The 19th IChO was held in Veszprem, Hungary, July 6–15, 1987.

 The 18th IChO was held in Leiden, Netherlands, July 6–15, 1986.

 The 17th IChO was held in Bratislava, Czechoslovakia, July 1–8, 1985.

 The 16th IChO was held in Frankfurt, West Germany, July 1–10, 1984.

 The 15th IChO was held in Timisoara, Romania, July 2–11, 1983.

 The 14th IChO was held in Stockholm, Sweden, July 3–12, 1982.

 The 13th IChO was held in Burgas, Bulgaria, July 13–23, 1981.

 The 12th IChO was held in Linz, Austria, July 13–23, 1980.

 The 11th IChO was held in Leningrad, Soviet Union, July 2–11, 1979.

 The 10th IChO was held in Torun, Poland, July 3–13, 1978.

 The 9th IChO was held in Bratislava, Czechoslovakia, July 4–14, 1977.

 The 8th IChO was held in Halle, East Germany, July 10–19, 1976.

 The 7th IChO was held in Veszprem, Hungary, July 1–10, 1975.

 The 6th IChO was held in Bucharest, Romania, July 1–10, 1974.

 The 5th IChO was held in Sofia, Bulgaria, July 1–10, 1973.

 The 4th IChO was held in Moscow, Soviet Union, July 1–10, 1972.

          The IChO was not held in 1971.

 The 3rd IChO was held in Budapest, Hungary, July 1–5, 1970.

 The 2nd IChO was held in Katowice, Poland, June 16–20, 1969.

 The 1st IChO was held in Prague, Czechoslovakia June 18–21, 1968.