In enzymology, a 6-aminohexanoate-cyclic-dimer hydrolase (EC 3.5.2.12) is an enzyme that catalyzes the chemical reaction

1,8-diazacyclotetradecane-2,9-dione + H₂O ${\displaystyle \rightleftharpoons }$ N-(6-aminohexanoyl)-6-aminohexanoate

Thus, the two substrates of this enzyme are 1,8-diazacyclotetradecane-2,9-dione and H₂O, whereas its product is N-(6-aminohexanoyl)-6-aminohexanoate.

This enzyme belongs to the family of hydrolases, those acting on carbon-nitrogen bonds other than peptide bonds, specifically in cyclic amides. The systematic name of this enzyme class is 1,8-diazacyclotetradecane-2,9-dione lactamhydrolase.