Phosphorous acid is an inorganic compound with the chemical formula H3PO3. It appears as a white crystalline powder, is highly soluble in water and ethanol, and slowly oxidizes to phosphoric acid in air. When heated to 180°C, it decomposes into phosphoric acid and phosphine. It is primarily used as a raw material in the production of plastic stabilizers and is also employed in the manufacture of synthetic fibers and phosphites.

Density: 1.651 g/cm3
Melting point: 73°C
Boiling point: 200°C
Appearance: White crystalline powder
Solubility: Highly soluble in water and ethanol
Density: 1.651 g/cm3
Melting point: 73°C
Boiling point: 200°C
Appearance: White crystalline powder
Solubility: Highly soluble in water and ethanol