Three new inorganic-organic hybrid compounds based on α-Keggin clusters and Ag-organic subunits, [Ag 3 L 4 (H 2 O) 4 ][PMo 12 O 40 ]·3H 2 O (1), [Ag 3 L 4 (H 2 O) 4 ][PW 12 O 40 ]·2H 2 O (2), and [Ag 3 L 6 ][PMo 12 O 40 ] (3) [L = 1-amino-4-(3,5-dimethylpyrazolyl)hydralazine], were synthesized under hydrothermal conditions and characterized by single-crystal X-ray diffraction. Compounds 1 and 2 are isostructural and contain two kinds of Ag subunits: dinuclear [Ag 2 L 2 (H 2 O) 4 ] 2+ and mononuclear [AgL 2 ] + . The dinuclear Ag clusters are linked by Keggin anions to construct a 1D chain, whereas