Glasses and melts of x%Na 2O-(100- x)%B 2O 3 ( x=40, 50, 60, 67 mol%) composition have been prepared and studied by high-temperature Raman spectroscopy. The regularities of the changes in structure of the melts are established as a function of the composition and temperature. Deconvolution analysis of obtained spectra was carried out in order to estimate both the fractions of short range order structures (SRO), BØ 3/2, [BØ 4/2] -, BØ 2/2O -, BO22- and BO33-, and to investigate the structural rearrangement of the intermediate range order structures (IRO). Equilibrium reactions were offered to describe the interaction between basic structural units in the melts. According to the analysis of SRO structures, some structural rearrangement models of the IRO structures were also proposed.