The title compound, [Cu(C(8)H(7)N(3))(2)(H(2)O)](3)[As(2)Mo(18)O(62)], consists of two subunits, viz. an α-Dawson-type [As(2)Mo(18)O(62)](6-) anion and a complex [Cu(C(8)H(7)N(3))(2)(H(2)O)](2+) cation. The copper(II) ion (site symmetry .2) is penta-coordinated in a distorted square-pyramidal manner by four N atoms from two chelating 3-(2-pyrid-yl)pyrazole ligands in equatorial positions and one water mol-ecule in the apical position. In the heteropolyanion, two O atoms of the AsO(4) group (3. symmetry) are equally disordered about the threefold rotation axis. N-H⋯O and O-H⋯O hydrogen bonding between the neutral mol-ecules and the water mol-ecules leads to a consolidation of the structure.