Aqueous solutions of 0.75NaPO₃ · 0.25NaF and 0.70LiPO₃ · 0.30LiF glasses are investigated by two-dimensional homonuclear correlation ³¹P-³¹P NMR spectroscopy. In the glass structures, the phosphate and fluorine-containing phosphate anions are identified and their NMR parameters are determined. A regular change in the spin-spin coupling constants and chemical shifts of the phosphorus atoms involved in the terminal [PO₃F] tetrahedra is observed with variations in the number of phosphorus atoms in the chain of fluorine-containing phosphate anions. Based on the experimentally obtained NMR parameters, the theoretical NMR spectra are calculated for difluoropolyphosphate anions with chain length of six to nine phosphorus atoms.