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).
Then in 1969, the first ISEO was organized in Leiden, the Netherlands with invited speakers. The Symposium Ätherische Öle was changed around 1980 into the International Symposium on Essential Oils (ISEO).
Series of ISEO conferences:
| Edition | Year | Venue | Host |
| 0 | initiation 1969 | Leiden, The Netherlands | A. Baerheim-Svendsen |
| 1 | 1970 | 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-Svendsen |
| 16 | 1985 | Holzminden/Neuhaus, Germany | E.-J. Brunke |
| 17 | 1986 | Bad Bevensen, Germany | E. Stahl-Biskup |
| 18 | 1987 | Nordwijkerhout, The Netherlands | 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, Ch. Franz |
| 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 |