The new layered germanate structure Na4Ge16O28(OH)(12) has been synthesized under hydrothermal conditions and characterized by single-crystal X-ray diffraction, FTIR, and SEM. The crystal lattice parameters are a = 7.3216(6) Angstrom, b = 14.3986(g) Angstrom, c = 7,7437(6) Angstrom, alpha = 90.0degrees, beta = 100.179(7)degrees, gamma = 90.0degrees, and V = 803.5(1) Angstrom(3). The space group is C2/m with Z = 1. The germanium oxide sheets are connected non-covalently via electrostatic interactions with the sodium cations and H-bridging. At temperatures above 400 degreesC, the structure starts decomposing into sodium enneagermanate (Na4Ge9O20), germanium dioxide, and water as determined by powder X-ray diffraction, TGA, DTA, DSC, and GCMS.