A new organically templated microporous zirconogermanate, (C2H10N2)H2O[ZrGe3O9] (denoted as FDZG-3), with a low framework density of 13.6 T/1000 Angstrom(3), has been solvo/hydrothermally synthesized by using ZrO(NO3)(2).2H(2)O as a zirconium source and triethylenetetramine (TETA) as a structure direct agent. This compound was characterized by means of single-crystal X-ray diffraction analysis, thermogravimetrical analysis, and IR and UV-vis spectra. Its three-dimensional (3D) framework is built up by 1D sinusoidal germanate chains cross-linked by ZrO6 octahedra, which forms a network containing three- and seven-membered rings (MRs). Four intersecting 7-MR channels can be observed along the b axis, c axis, [110], and [-110] directions, respectively. Charge-balancing (C2H10N2)(2+) and extraframework water molecules are encapsulated within 7-MR channels and form hydrogen bonds with framework oxygen atoms. Crystal data for FDZG-3: M = 533.13, monoclinic, space group Cc (No.9), a = 11.299(3) Angstrom, b = 7.7649(19) Angstrom, c = 13.835(3) Angstrom, beta = 104.826(3)degrees, V = 1173.4(5) Angstrom(3), Z = 4, R1 = 0.0263, wR2 = 0.0529.