In enzymology, a bromoxynil nitrilase (EC 3.5.5.6) is an enzyme that catalyzes the chemical reaction

3,5-dibromo-4-hydroxybenzonitrile + 2 H₂O 3,5-dibromo-4-hydroxy-benzoate + NH₃

Thus, the two substrates of this enzyme are 3,5-dibromo-4-hydroxybenzonitrile and H₂O, whereas its two products are 3,5-dibromo-4-hydroxy-benzoate and NH₃.

This enzyme belongs to the family of hydrolases, those acting on carbon-nitrogen bonds other than peptide bonds, specifically in nitriles. The systematic name of this enzyme class is 3,5-dibromo-4-hydroxybenzonitrile aminohydrolase. This enzyme participates in 1,4-dichlorobenzene degradation.

• Stalker DM, Malyj LD, McBride KE (1988). "Purification and properties of a nitrilase specific for the herbicide bromoxynil and corresponding nucleotide sequence analysis of the bxn gene". J. Biol. Chem. 263 (13): 6310–4. PMID 2834373.