As a comparatist, Wittmann contributed to the study of the morphology of a number of languages and language families: Pre-Indo-European, Indo-European (Hittite, Italic, Romance, Germanic, Creole), Afro-Asiatic (Egyptian), African (Mande, Kwa, Bantu), Austronesian (Malagasy, Polynesian), Amerindian (Arawakan, Cariban).
In 1981, he was the cofounder, with Normand Beauchemin and Robert Fournier, of the Linguistic Society of Quebec (Association québécoise de linguistique) which he served for 10 years as president, secretary general and organizer of the annual meeting.
Politically, Wittmann is known for his anarcho-syndicalist sympathies with strong links to the CNTU (Confederation of National Trade Unions), communautary and anti-war movements.
[3] Henri Wittmann is the first modern linguist to study non-standard forms of Quebec French (notably Joual, Magoua and Chaouin) in a theory-orientated and comparative framework.
In a general way, Wittmann, a student of André Martinet in the fifties,[4] has been the first to apply the latter's principles of chain reactions in phonology to inflectional morphology.