During the Revolution Barthélemy was arrested (September 1793) as an aristocrat and confined in a prison for a few days. The Committee of Public Safety, however, were no sooner informed by the Duchess of Choiseul of the arrest than they gave orders for his immediate release, and in 1793 he was nominated librarian of the Bibliothèque Nationale. He refused this post but resumed his old functions as keeper of medals, and enriched the national collection by many valuable accessions.