The enzyme gentisate decarboxylase () catalyzes the chemical reaction
This enzyme belongs to the family of lyases, specifically the carboxy-lyases, which cleave carbon-carbon bonds. The systematic name of this enzyme class is 2,5-dihydroxybenzoate carboxy-lyase (hydroquinone-forming). Other names in common use include 2,5-dihydroxybenzoate decarboxylase, and gentisate carboxy-lyase. This enzyme participates in tyrosine metabolism.