While at the Lycée Louis-le-Grand Kaan founded a literary review called la Gerbe du Quartier Latin, alongside fellow students Daniel Guérin, Georges Altman, and Paul Verdier.

[4][5] In 1931 Pierre Kaan began his involvement with Boris Souvarine's La Critique Sociale joining Bataille, Weil, Queneau, Lucien Laurat and other writers, philosophers and economists to revue letters and ideas for what would become a widely read publication during the 1930s.

On 6 January 1942, Kaan plays an important part in organising a large demonstration against the departure of workers following a speech made by Pierre Laval – the Nazi collaborating Prime Minister of the Vichy Régime.

[6] Following the success of his operations in Montluçon, Pierre Kaan is named Jean Moulin's deputy responsible for safeguarding transport and communication links between Lyon and the occupied half of France.

[6] Denounced by a close collaborator in the winter of 1943, Pierre Kaan was arrested by the Gestapo on 29 December on the steps of Port-Royal métro station in Paris, tortured and then deported to Buchenwald concentration camp.

On 12 May 1948, the official journal of the French Government announced that Kaan had been posthumously decorated with Knight of the Legion of Honour, Medal of the Resistance with Rosette, War Cross with silver palm.