International Symposium of Essential oils (ISEO) idea was initiated in 1968 at the GA meeting in Würzburg, Germany during the discussions of Profs. Anders Baerheim Svendsen, Karl-Heinz Kubeczka, Friedrich Wilhelm Hefendehl and Dr. Jan Karlsen.
It was proposed to hold a discussion group for all aspects of essential oils (separation of terpenes, chemistry, chemotaxonomy or other relevant topics regarding the constituents of essential oils).
In 1969, an informal meeting was organized by F. W. Hefendehl (University of Freiburg, FRG), K.-H. Kubeczka (Technical University of Karslruhe, FRG). Dr J. Karlsen and Professor A. Baerheim Svendsen (both State University of Leiden, The Netherlands).
The first Symposia, organized from 1971 to around 1980, were named as Symposium Ätherische Öle and, then, changed into International Symposium on Essential Oils (ISEO).
Series of ISEO conferences:
| Edition | Year | Venue | Host |
| 1 | 1969 | Leiden, The Netherlands | A. Baerheim Svendsen |
| 2 | 1971 | Freiburg, Germany | F.W. Hefendehl |
| 3 | 1972 | Helsinki, Finland | M. von Schantz |
| 4 | 1973 | Freiburg, Germany | F.W. Hefendehl |
| 5 | 1974 | Freiburg, Germany | F.W. Hefendehl |
| 6 | 1975 | Leiden, The Netherlands | A. Baerheim Svendsen |
| 7 | 1976 | Würzburg, Germany | K.-H. Kubeczka |
| 8 | 1977 | Freiburg, Germany | F.W. Hefendehl |
| 9 | 1978 | Münster, Germany | H. Hörster |
| 10 | 1979 | Würzburg, Germany | K.-H. Kubeczka |
| 11 | 1980 | Groningen, The Netherlands | M.H. Boelens, H. Hendriks |
| 12 | 1981 | Marburg, Germany | K.-H. Kubezka |
| 13 | 1982 | Würzburg, Germany | K.-H. Kubeczka |
| 14 | 1983 | Freising-Weihenstephan, Germany | Ch. Franz |
| 15 | 1984 | Leiden, The Netherlands | A. Baerheim Svensen, J.J.C. Scheffer |
| 16 | 1985 | Holzminden/Neuhaus, Germany | E.-J. Brunke |
| 17 | 1986 | Bad Bevensen, Germany | E. Stahl-Biskup |
| 18 | 1987 | Leiden, The Netherlands | A. Baerheim Svensen, J.J.C. Scheffer |
| 19 | 1988 | Zürich-Greifensee, Switzerland | D. Lamparsky, R. Kaiser |
| 20 | 1989 | Würzburg, Germany | K.-H. Kubeczka |
| 21 | 1990 | Lahti, Finland | R. Hiltunen |
| 22 | 1991 | St.Vincent, Italy | C. Bicchi |
| 23 | 1992 | Auchincruive, UK | S. Deans, K. Svoboda |
| 24 | 1993 | Berlin, Germany | P. Weyerstahl, H. Schilcher |
| 25 | 1994 | Grasse, France | D. Joulain |
| 26 | 1995 | Hamburg, Germany | K.-H. Kubeczka |
| 27 | 1996 | Wien/Vienna, Austria | Ch. Franz, G. Buchbauer |
| 28 | 1997 | Eskisehir, Turkey | K.H.C. Baser, N. Kirimer |
| 29 | 1998 | Frankfurt, Germany | W. König, A. Mosandl |
| 30 | 1999 | Leipzig/Miltitz, Germany | Bell Flavours & Fragrances |
| 31 | 2000 | Hamburg, Germany | K.-H. Kubeczka, W. König |
| 32 | 2001 | Wroclaw, Poland | S. Lochynski |
| 33 | 2002 | Lisbon, Portugal | A. Figueiredo |
| 34 | 2003 | Würzburg, Germany | K.-H. Kubeczka |
| 35 | 2004 | Giardini Naxos, Italy | L. Mondello, G. Dugo |
| 36 | 2005 | Budapest, Hungary | E. Nemeth |
| 37 | 2006 | Grasse, France | D. Joulain |
| 38 | 2007 | Graz, Austria | Ch. Franz, J. Novak, R. Bauer |
| 39 | 2008 | Quedlinburg, Germany | J. Schulz |
| 40 | 2009 | Savigliano, Italy | C. Bicchi, P. Rubiolo |
| 41 | 2010 | Wroclaw, Poland | S. Lochynski |
| 42 | 2011 | Antalya, Turkey | K.H.C. Baser, F. Demirci |
| 43 | 2012 | Lisbon, Portugal | A. Figueiredo |
| 44 | 2013 | Budapest, Hungary | E. Nemeth |
| 45 | 2014 | Istanbul, Turkey | K.H.C. Baser, F. Demirci |
| 46 | 2015 | Lublin, Poland | A. Ludwiczuk |
| 47 | 2016 | Nice, France | N. Baldovini |
| 48 | 2017 | Pecs, Hungary | G. Horvath |
| 49 | 2018 | Nis, Serbia | N. Radulovic |
| 50 | 2019 | Vienna, Austria | J. Novak, I. Stappen |
| 51 | 2021 | Nicosia, N. Cyprus (On-line) | K.H.C. Baser, F. Demirci |
| 52 | 2022 | Wroclaw, Poland | S. Lochynski, D. Strub |
| 53 | 2023 | MIlazzo, Italy | P. Dugo, L. Mondello |
| 54 | 2024 | Balatonalmádi, Hungary | G. Horváth, É. Németh-Zámboriné |