[1] Ettre was born in Szombathely, Hungary and received a degree equivalent to a Masters of Science in Chemical Engineering in 1946 from the Technical University, Budapest.
In 1956 he was appointed to the position of head of the Industrial Department of the Hungarian Research Institute on Plastics in Budapest.
He held the position of chemical engineer at Lurgi AG in Frankfurt am Main, West Germany, where he began to work with gas chromatography.
Ettre was a member of the Commission on Analytical Nomenclature of the International Union of Pure and Applied Chemistry (I.U.P.A.C.)
In 2008, the Leslie Ettre Award of the International Symposium on Capillary Chromatography was established by the PerkinElmer Corporation.