The structure of alkali berate glasses and melts with 10, 20 and 30 mol% K2O have been studied by high-temperature Raman spectroscopy. Not only with an increase of K2O content but also with increasing temperature, boroxol rings in the potassium berate glass/melt have converted to pentaborate groups which consist of BO4- tetrahedra (O = bridging oxygen atom) and metaborate, BO2O-, triangular units. Furthermore, Raman spectra have indicated a structural change of berate species from BO4 tetrahedral units to BO3 triangles with non-bridging oxygen with increasing temperature in 30 mol% K2O-B2O3 glass. The fraction of four-coordinated boron atoms, N-4, was obtained and found to exhibit a gradual reduction above the glass transition temperature in this glass.