Jean-Jacques Barthélemy (20 January 1716 – 30 April 1795)[1] was a French Catholic clergyman, archaeologist, numismatologist and scholar who became the first person to decipher an extinct language.

[3] In 1744, he went to Paris with a letter of introduction to Claude Gros de Boze, Perpetual Secretary of the Académie des inscriptions et belles-lettres and Keeper of the Royal Collection of Medals.

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.

[14][15] The Palmyrene alphabet was deciphered in 1754, literally overnight, by Abbé Jean-Jacques Barthélemy using these new, accurate copies of bilingual inscriptions.

[16] Abbot Jean-Jacques Barthélemy, working with Anne Claude de Caylus, identified that non-hieroglyphic cursive Egyptian scripts seemed to consist of alphabetical letters graphically derived from hieroglyphs, in Recueil d'antiquités égyptiennes, 1752.

[11] Barthélémy was also the first to suggest, in volume V of the Recueil of Count Caylus, published in 1762, that the signs in Egyptian cartouches probably represented royal names.

See also Mémoires sur la vie de l'abbé Barthélemy, écrits par lui-même (1824), with a notice by Lalande.