In 1615, he was commissioned by Mathieu Molé, first president of the parlement of Paris, to draw up an inventory of the documents which constituted what at that time was known as the Trésor des chartes.
His manuscript inventory is preserved in the original and in copy in the Bibliothèque Nationale, and transcriptions are in the national archives in Paris, at the record office in London,and elsewhere.
Dupuy also published, with his brother Jacques, and their friend Nicolas Rigault, the History of Aug. de Thou (1620, 1626).
They were written from the Gallican standpoint, i.e. in favour of the rights of the crown in temporal and political matters, and this explains the delay in their publication until after Dupuy's death.
See also Léopold Delisle's Le Cabinet des manuscrits de la Bibliothèque impériale.