The crystal structure of H-LDS (Si8O20H8)-an acidified form of the layered silicate K-LDS was determined. Structure analysis from X-ray powder diffraction data shows that its layer structure comprises a six-membered Si atom ring network. H-1 MAS NMR spectroscopy indicates strong intra- and inter-layer hydrogen bonding between neighboring terminal oxygen atoms. Electron density distributions attributed to hydrogen bonding are obtained by the maximum entropy method. The structure of H-LDS is stabilized by the hydrogen bonds without an alkali metal cation.