A complete literature review, critical evaluation, and thermodynamic modeling of the phase diagrams and thermodynamic properties of all oxide phases in the binary systems B₂O₃ – SiO₂ and B₂O₃ – Al₂O₃ have been performed. The molten oxide is described by the Modified Quasichemical Model. Discrepancies in the available experimental data have been resolved and an optimized set of self-consistent thermodynamic functions of all phases has been obtained. This thermodynamic database can be used with the FactSage^TM thermodynamic computing system to calculate all thermodynamic properties and phase equilibria from 25 °C to above the liquidus temperatures at 1 atm of total pressure and over the entire composition range.