Oxalacetic acid (Oxaloacetic acid, 2-Oxosuccinic acid, Ketosuccinic acid) is an intermediate of the citric acid cycle, where it reacts with acetyl-CoA to form citrate, catalysed by citrate synthase. It is also involved in gluconeogenesis, urea cycle, glyoxylate cycle, amino acid synthesis, and fatty acid synthesis. Oxaloacetate is also a potent inhibitor of Complex II.