After his thesis, Michel Niclause became Associate Professor (Maître de Conférences) at ENSIC in 1954. From 1950 to 1955 he was also lecturer at Sarre University in Germany. At the young age of 34 years, he became head of the General Chemistry Chair at ENSIC. He kept this position until he retired in 1983.
1968, he founded a CNRS research team (ERA n°136) which he directed until 1983. This research team became later the Département de Chimie Physique des Réactions (DCPR: Department of Physical Chemistry of Reactions); 2010, the laboratory merged with other laboratories to become the LRGP. Michel Niclause was a Member of the Académie Lorraine des Sciences; he received the Prix Philippe Guye, the Prix Gegner and the Médaille Berthelot of the French Académie des Sciences ; he was Knight of the Legion of Honour.
Michel Niclause was a leading specialist of homogeneous particularly radical chemical kinetics. His research range was large: pyrolysis, oxidation, photo-oxidation, combustion, control of energy and matter waste, pollution control, food industry, biology, medicine. An article published in 1978 was still cited in 2015
He identified with Letort and their Belgian colleague professor Paurl Goldfinger radical decompoistion rules, called . These rules are the basis of the development of automatic mechanism generation programmes for pyrolysis and combustion reactions, as the EXGAS system in Nancy, and SPYRO in Milano.
Due to the reputation of professor Niclause, a number of professors from abroad spend a sabbatical leave in Nancy: Prof. W.A. Noyes jr. from Texas University at Austin (1969), Prof. H.E. O’Neal from the San Diego University (1980-81).
Numerous PhD students of Michel Niclause occupied important positions at university, CNRS and industry: e.g. his first PhD student, René Martin, made his research career at DCPR and became porfessor at Université Nancy I, René Baronnet, research director at CNRS was the head of DCPR from 1989 to 1999.