[1] He studied at the École des beaux-arts de Montréal in 1937 but after three years left as he found the teaching too conservative.
In 1948, he helped compose the manifesto which Alfred Pellan used to establish the Prisme d'yeux group.
"We seek a painting freed from all contingencies of time and place, of restrictive ideology, conceived without any literary, political, philosophical or other meddling which could dilute its expression or compromise its purity" stated a translation of Prisme d'yeux that was published in Canadian Art.
[5] This group opposed those who would sign the Refus Global later that year, feeling that painting should not be a political act.
In 1958, works by de Tonnancour along with those of James Wilson Morrice, Anne Kahane and Jack Nichols represented Canada at the Venice Biennale.