In enzymology, D-aspartate oxidase () is an enzyme that catalyzes the chemical reaction
The three substrates of this enzyme are D-aspartic acid, water and oxygen. Its products are oxaloacetic acid, hydrogen peroxide, and ammonia.
This enzyme belongs to the FAD dependent oxidoreductase family, specifically those acting on the CH-NH<sub>2</sub> group of donors with oxygen as acceptor. The systematic name of this enzyme class is D-aspartate:oxygen oxidoreductase (deaminating). Other names in common use include aspartic oxidase, and D-aspartic oxidase. This enzyme participates in alanine and aspartate metabolism. It employs one cofactor, FAD.
The enzyme is encoded by DDO gene.