In the title compound, [CuMoO(4)(C(8)H(20)N(4))]·H(2)O, the Cu(II) atom is coordinated by four N atoms of the 1,4,7,10-tetra-aza-cyclo-dodecane (cyclen) ligand and one O atom of the molybdate unit in a distorted square-pyramidal environment. The water mol-ecules are linked to the complex unit to form centrosymmetric dimers [R(4) (4)(12) and R(4) (4)(16)] and discrete D(3) (2)(9), D(3) (3)(11) a...