The hydrogen bonding in concentrated aqueous solutions of 1,2-dimethoxyethane was studied by Raman spectroscopy of the O-H stretching band of water at various concentrations in the temperature range 218-315 K. The isotropic Raman spectra were analyzed by band decomposition, and two major components were identified in the spectra. They were assigned to the O-H stretching vibrations of water monomers and water molecules participating in clusters. respectively. The following picture of the hydration structure in the solutions emerged. Water molecules in concentrated aqueous solutions of 1.2-dimethoxyethane can exist in two stable configurations-either participating in water clusters enclosed in cavities of 1,2-dimethoxyethane molecules, or as monomers bridging ether oxygen atoms. The clustering of water is driven by the cooperative strengthening of the hydrogen bonds in the clusters. The clusters and the cavities are mutually stabilized by the extensive hydrogen bonding, and the size of the clusters is almost independent of temperature.