A novel octamolybdate-type polyoxometalate-based solid ([{Cu(pzc)2}Mo8O26] 8H2O) (Cu POM) was synthesized, and is a redox-active species for nitrate electroreduction. More specifically, the Cu POM exhibits an excellent faradaic efficiency and yield rate of 78.3% and 11.9 mg h cm-2, respectively, in 1 M KOH containing 0.1 M KNO3.