Former Secretary-Generals
| Secretary-General | Period | Official Headquarters of the Institute |
| Marcelo G. Kohen | from 2015 to 2024 | Geneva (Switzerland) |
| Joe Verhoeven | from 2003 to 2015 | Grez-Doiceau (Belgium) |
| Christian Dominicé | from 1991 to 2003 | Geneva (Switzerland) |
| Nicolas Valticos | from 1981 to 1991 | Geneva (Switzerland) |
| Paul De Visscher | from1969 to 1981 | Brussels (Belgium) |
| Mme Suzanne Bastid | from 1963 to 1969 | Paris (France) |
| Paul Guggenheim (interim) | from 1962 to 1963 | Geneva (Switzerland) |
| Hans Wehberg | from 1950 to 1962 | Geneva (Switzerland) |
| Fernand De Visscher | from 1937 to 1950 | Brussels (Belgium) |
| Charles De Visscher | from 1927 to 1937 | Ghent (Belgium) (1927-1931) Brussels (Belgium) (1931-1937) |
| Alfred Nerincx | from 1923 to 1927 | Louvain (Belgium) |
| Albéric Rolin | from 1906 to 1923 | Ghent (Belgium) (1906-1913) The Hague (The Netherlands) (1913-1919) Brussels (Belgium) (1931-1937) |
| Edouard Descamps | from 1900 to 1906 | Louvain (Belgium) |
| Ernest Lehr | from 1892 to 1900 | Lausanne (Switzerland) |
| Gustave Rolin-Jaequemyns | from 1887 to 1892 | Brussels (Belgium) |
| Alphonse Rivier | from 1878 to 1887 | Brussels (Belgium) |
| Gustave Rolin-Jaequemyns | from 1873 to 1878 | Ghent (Belgium) |
