Alexandre Léon Étard (1852–1910) was a French chemist.

[2][3] Étard was a preparer at the Wurtz Laboratory at École Pratique des Hautes Études, and became a member of the Société de Chimie Industrielle in 1875.

He studied at the Sorbonne, and earned a Doctorate in Physical Sciences in 1880.

[1] Étard discovered the oxidation reaction of methyl groups linked to aromatic rings or to heterocycles using chromyl chloride, known as the Étard reaction.

Chromyl chloride is sometimes also called "Étard reagent."