 The research of Henneaux is devoted to the study of the theoretical models describing the fundamental physical interactions (electromagnetism, weak and strong nuclear forces, gravity), with a particular emphasis on their symmetries.With J.David Brown, he showed that Einstein theory of gravity in three spacetime dimensions with a negative cosmological constant possesses a remarkable symmetry structure at infinity described by two Virasoro algebras.The corresponding central charge bears the name of "Brown-Henneaux central charge".