Commencing in 1966 to work as a child and adolescent psychotherapist he made some attempts to art therapy. This turned out so well that from then on he originated the "Atelier d’art-thérapie". All painted works by the patients during this therapy were collected and donated to the Museum of Hospice St. Roch in Issoudun.
Further he collaborated with the "Institut Édouard Claparède de Neuilly-sur-Seine"
One year later, in 1969 Soisson joined the Société d’Art Brut, having been founded by Jean Dubuffet. It ensued an acquaintance between both.
In 1978 Jacques Soisson gave up his profession and dedicated to painting, animated by Dubuffet.
He lived and painted in Paris.