PEC studies on the single crystals of a metal-cluster oxide compound, Zn//2Mo//3O//8 are reported for the first time. The photoresponse is attributed to the molybdenum d-d transition from the filled d-valence band to the empty conduction band. Preliminary results show that Zn//2Mo//3O//8 possesses all the requisite characteristics of an ideal photoanode for PAE of water for trapping solar energy. Improvements are possible because of the existence of isostructural series where Zn can be substituted by other M**2** plus ion or (LiLn**3** plus ) (Ln equals lanthanides).