Furfural (C₄H₃O.CHO), also known as 2-furaldehyde and furan-2-carboxaldehyde, is a colorless, oily liquid, an aldehyde similar to benzaldehyde, and a heterocyclic compound derived from furan. It smells of almonds and quickly turns yellow when exposed to air.

Furfural is made by digesting corncobs, oat, and rice hulls, etc. with acid, and is used as a solvent, a pesticide, and an intermediate in making plastics and other compounds. Its name comes from the Latin furfur, meaning "bran."