Hypophosphoric acid has an effective content of 50%. It is a monoprotic oxyacid with strong reducing properties. It can be used in electroless nickel plating, to prevent discoloration of phosphate resins, as a catalyst in organic synthesis, a refrigerant, and in food processing and preservation, as well as in the production of nickel/hydrogen battery cathodes. Currently, hypophosphoric acid is mainly produced domestically using sodium hypophosphorus through processes such as ion-exchange membranes. Its molecular structure, properties, and characteristics are briefly described below:

Molecular formula: H3PO2, relative molecular mass: 65.97. H3PO2 has a tetrahedral configuration, with two hydrogen atoms directly bonded to the central phosphorus atom, and the other hydrogen atom bonded to an oxygen atom. Therefore, hypophosphoric acid is a monoprotic acid. Although H3PO2 exhibits the following tautomerisms, the equilibrium strongly shifts to the left.

Density 1.1 g/cm³, boiling point 107.8℃, colorless and transparent liquid, saturated vapor pressure (20℃) <2.27 kPa. Easily soluble in hot water, ethanol, and ether. Soluble in cold water. When heated to 130℃, it decomposes into orthophosphoric acid and PH3. H3PO2 is a strong reducing agent. Anhydrous hypophosphoric acid crystals are stable at room temperature and show no change after being placed in dry air for 3 months. In actual industrial production, anhydrous H3PO2 does not exist; its existence is purely theoretical.

Hypophosphoric acid (H3PO2) is a monoprotic moderately strong acid with an ionization constant K. = 8.5 × 10⁻². It can react with bases to form a series of salts. H3PO2 and its salts have strong reducing properties and can reduce metal ions such as copper, nickel, and mercury to their corresponding metals.