Two new polyoxometalate(POM)-based hybrid compounds, [Cu(en)][H 4 Mo 4 O 16 ] 0.5 (1)(en=ethylene-diamine) and [Ag(3-C 5 H 6 N 2 ) 2 ][H 2 PMo 12 O 40 ](2)(3-C 5 H 6 N 2 =3-aminopyridine), containing different transition metalamine subunits were hydrothermally synthesized and characterized by elemental analyses, infrared spectroscopy and single-crystal X-ray diffraction. For compound 1, each [H 4 Mo 4 O 16 ] 4-(Mo 4 O 16 ) cluster was linked to four neighboring Mo 4 O 16 clusters through four [Cu(en)] 2+ subunits to yield a (2,4)-connected 2D layer, which was further extended to a 3D supramolecular network via hydrogen bonding interactions. For compound 2, the adjacent [H 2 PMo 12 O 40 ] -clusters were bridged by H 6 N 2 ) 2 ] + subunits to generate a 1D chain. The electrochemical behaviors and the photocatalytic activities of compounds 1 and 2 were studied in detail.