In enzymology, a selenate reductase (EC 1.97.1.9) is an enzyme that catalyzes the chemical reaction selenite + H2O + acceptor rightleftharpoons selenate + reduced acceptor. The 3 substrates of this enzyme are selenite, H2O, and acceptor, whereas its two products are selenate and reduced acceptor. This enzyme belongs to the family of oxidoreductases. The systematic name of this enzyme class is selenite:reduced acceptor oxidoreductase.