Dipeptidyl peptidase 10 (DPP10, DPPY) is an inactive peptidase associated with voltage-gated potassium channels, acting as a modulator of their electrophysiological properties, cell-surface expression and subcellular localization. Because potassium channels are important disease targets, biochemical and structural characterization of their interaction partners was sought. DPP10 was cloned and expressed using an insect-cell system and the protein was purified via His-tag affinity and size-exclusion chromatography. Crystals obtained by the sitting-drop method were orthorhombic, belonging to space group P2(1)2(1)2(1) with unit-cell parameters a = 80.91, b = 143.73, c = 176.25 Å. A single solution with two molecules in the asymmetric unit was found using the structure of DPP6 (also called DPPX; PDB entry 1xfd) as the search model in a molecular replacement protocol.