Several series of SrTiO3-aluminoborate and SrTiO3-aluminoborosilicate glasses were prepared, which exhibited low corrosion rates in water at 90 °C. The additions of up to 9 mol% P2O5 to these glasses were found to significantly improve the chemical durability. The weight loss rate of a glass with the nominal composition (mol%) 15SrO-15TiO2-23.3Al2O3-46.7B2O3 decreased by over two orders of magnitude with the additions of up to 9 mol% P2O5. In contrast, P2O5-additions increased the dissolution rate of the silicate analog of the initial borate glass, 15SrO-15TiO2-23Al2O3-47SiO2. The positive effect of small P2O5 additions on the chemical durability of the aluminoborate glasses may be attributed to the replacement of BO3 units by BO4 units in the glass network, as indicated by infrared and Raman spectra.