In enzymology, a carnitine dehydratase () is an enzyme that catalyzes the chemical reaction
Hence, this enzyme has one substrate, L-carnitine, and two products, 4-(trimethylammonio)but-2-enoate and H<sub>2</sub>O.
This enzyme belongs to the family of lyases, specifically the hydro-lyases, which cleave carbon-oxygen bonds. The systematic name of this enzyme class is L-carnitine hydro-lyase [4-(trimethylammonio)but-2-enoate-forming]. This enzyme is also called L-carnitine hydro-lyase.