In enzymology, a diphosphoinositol-polyphosphate diphosphatase () is an enzyme that catalyzes the chemical reaction
Thus, the two substrates of this enzyme are diphospho-myo-inositol polyphosphate and H<sub>2</sub>O, whereas its two products are myo-inositol polyphosphate 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 diphospho-myo-inositol-polyphosphate diphosphohydrolase. Other names in common use include diphosphoinositol-polyphosphate phosphohydrolase, and DIPP.
As of late 2007, 3 structures have been solved for this class of enzymes, with PDB accession codes , , and .