Its aqueous solution is strongly alkaline.

　　Heating to 55 ~ 65℃ into ten water sodium phosphate, heating to 60 ~ 100℃ into six water sodium phosphate, heating to 100℃ above to become sodium phosphate, heating to 212℃ above to become anhydrous sodium phosphate. In dry air easy to deliquescence weathering, the formation of sodium dihydrogen phosphate and sodium bicarbonate. It is almost completely decomposed into disodium hydrogen phosphate and sodium hydroxide in water.