Potassium dihydrogen phosphate is a colorless tetragonal crystal or a white crystalline powder. The relative density is 2.338. Melting point 252.6°C. Soluble in water, at 90°C, the solubility is 83.5g/100ml water, the aqueous solution is acidic, and the pH of 1% potassium dihydrogen phosphate solution is 4.6. Insoluble in alcohol. Deliquescence. When heated to 400°C, it melts into a transparent liquid, which cools to an opaque glassy potassium metaphosphate.