Enthalpies above 298 deg k were investigated for four crystalline sodium borates by copper-block drop calorimetry. Determinations were made to 1,200 deg k for nabo2, 1,003 deg k for na2b4o7, 1,005 deg k for nab3o5, and 1,046 deg k for na2b8o13. No phase transitions or other thermal anomalies were found. The enthalpy determinations, when combined with known heats of formation at 298 deg k and other supplementary data, enabled the calculation of the heats and free energies of formation of the compounds to their melting points. Values of relative enthalpies, entropies, heat capacities, free energy functions, enthalpies of formation, free energies of formation, and equilibrium constants of formation were tabulated at even temperatures.