He studied music from 1955–57 at the Conservatoire de musique du Québec à Montréal with Germaine Malépart (piano) and at the University of Montreal with Jean Papineau-Couture (acoustics), Gabriel Cusson and Conrad Letendre (harmony and counterpoint) and Jean Vallerand (music history).
In 1960 in Paris, with Gail Grimstead (flute) and Jacques Simard (oboe), he founded the "Trio canadien"; it toured 1962–63 for the JMC, giving the premiere of André Prévost's "Triptyque".
Appointed assistant to Zubin Mehta, the MSO's artistic director, Hétu was responsible for conducting the Matinées symphoniques; he held the position until 1968.
10, a work which 'can only be sustained by a conductor possessing authority, panache, and an intuitive feel for the music,' Gilles Potvin wrote: 'Hétu literally propelled the MSO to a grandiose and spacious performance, with an inspirational sweep that did not let up for a single moment and called to mind a Kondrashin or a Mravinsky' (Montreal Le Devoir 30 January 1975).
In 1977 he led the Nouvel orchestre philharmonique de Paris in works by Jacques Hétu, Matton, and Prévost (see Musicanada).