In enzymology, a copalyl diphosphate synthase () is an enzyme that catalyzes the chemical reaction
Hence, this enzyme has one substrate, geranylgeranyl diphosphate, and one product, (+)-copalyl diphosphate.
This enzyme belongs to the family of isomerases, specifically the class of intramolecular lyases. The systematic name of this enzyme class is (+)-copalyl-diphosphate lyase (decyclizing). This enzyme participates in diterpenoid biosynthesis.