Pierre-Auguste, chevalier Adet (French pronunciation: [pjɛʁ oɡyst ʃəvalje adɛ]; 17 May 1763 Nevers – 19 March 1834 Paris) was a French scientist, politician, and diplomat.

He worked with Lavoisier on a new chemical notation system, and was secretary to the scientific periodical Annales de chimie, founded in 1789.

[1] In 1796, Adet was elected a member of the American Philosophical Society.

[2] He was secretary to the Minister of the Navy and the Colonies, Jean Dalbarade.

He later became French ambassador to the United States, He sent Georges-Henri-Victor Collot on a reconnaissance of the Ohio River, and Mississippi River.