In enzymology, a triphosphatase () is an enzyme that catalyzes the chemical reaction
Thus, the two substrates of this enzyme are triphosphate and H<sub>2</sub>O, whereas its two products are diphosphate and phosphate.
This enzyme belongs to the family of hydrolases, specifically those acting on acid anhydrides in phosphorus-containing anhydrides. The systematic name of this enzyme class is triphosphate phosphohydrolase. This enzyme is also called inorganic triphosphatase.