Xanthine dehydrogenase/oxidase (XDH/XO) antibodies are immunological tools used to detect and study the enzyme XDH, which plays a dual role in purine metabolism and reactive oxygen species (ROS) production. XDH is a molybdenum-containing enzyme that catalyzes the oxidation of hypoxanthine to xanthine and xanthine to uric acid, a key step in purine catabolism. Under physiological conditions, XDH exists primarily in its dehydrogenase form (XDH), utilizing NAD⁺ as an electron acceptor. However, under stress or inflammation, it can be converted to its oxidase form (XO), which generates ROS like superoxide and hydrogen peroxide, contributing to oxidative tissue damage. Dysregulation of XDH/XO activity has been implicated in pathologies such as ischemia-reperfusion injury, chronic inflammation, fibrosis, and cardiovascular diseases. Antibodies targeting XDH are essential for quantifying its expression in tissues or biofluids, assessing its subcellular localization, and investigating its role in disease models. They are widely used in techniques like Western blotting, immunohistochemistry, and ELISA. Research using XDH antibodies has also explored its potential as a biomarker and therapeutic target, particularly in conditions linked to hyperuricemia (e.g., gout) or oxidative stress. Inhibitors of XO, such as allopurinol, are already clinically used, underscoring the enzyme's biomedical significance. These antibodies thus serve as critical reagents in both basic research and translational studies of metabolic and oxidative disorders.