CN-deficient Prussian blue analogues (PBAs), [M-N(H2O)(x)](y)[Fe-II(CN)(5)(NH3)] (M-N = Cu-II, Co-II, or Ga-III), were synthesized and examined as a new class of heterogeneous catalysts for hydrolytic decomposition of organophosphates often used as pesticides. The active species of the CN-deficient PBAs were mainly C-bound Fe-II ions with only single open sites generated by liberation of the NH3 ligand during the catalytic reactions. [Cu-II(H2O)(8/3)](3/2)[Fe-II(CN)(5)(NH3)] showed higher catalytic activity than [Co-II(H2O)(8/3)](3/2)[Fe-II(CN)(5)(NH3)] and [Ga-III(H2O)][Fe-II(CN)(5)(NH3)], although N-bound Cu-II species has been reported as less active than Co-II and Ga-III species in conventional PBAs. IR measurements of a series of the CN-deficient PBAs after the catalytic reactions clarified that a part of the NH3 ligands remained on [CoII(H2O)(8/3)](3/2)[Fe-II(CN)(5)(NH3)] and that hydrogen phosphate formed as a product strongly adsorbed on the Fe-II ions of [Ga-III(H2O)][Fe-II(CN)(5)(NH3)]. Hydrogen phosphate also adsorbed, but weakly, on the Fe-II ions of [Cu-II(H2O)(8/3)](3/2)[Fe-II(CN)(5)(NH3)]. These results suggest that heterogeneous catalysis of the Fe-II ions with single open sites were tuned by the MN ions through metal-metal interaction.