Sodium hypophosphite

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Sodium hypophosphite
One sodium cation and one hypophosphite anion
Ball-and-stick model of the component ions
CAS number 7681-53-0 YesY
10039-56-2 (monohydrate)
PubChem 16129646
ChemSpider 22758 YesY
RTECS number SZ5640000 (monohydrate)
Jmol-3D images Image 1
Molecular formula NaPO2H2
Molar mass 87.98 g/mol (anhydrous)
105.99 g/mol (monohydrate)
Appearance white solid
Density 0.8 g/cm3 (monohydrate)
Melting point 90 °C (194 °F; 363 K) (monohydrate)
Solubility in water soluble
EU Index Not listed
Flash point Non-flammable
Related compounds
Other anions Sodium phosphite
Monosodium phosphate
Disodium phosphate
Trisodium phosphate
Other cations Potassium hypophosphite
Related compounds Hypophosphorous acid
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
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Infobox references

Sodium hypophosphite (NaPO2H2, also known as sodium phosphinate) is the sodium salt of hypophosphorous acid and is often encountered as the monohydrate, NaPO2H2·H2O. It is a solid at room temperature, appearing as odorless white crystals. It is soluble in water, and easily absorbs moisture from the air.

Sodium hypophosphite should be kept in a cool, dry place, isolated from oxidizing materials. It decomposes when heated and produces toxic phosphine gas, causing irritation to the respiratory tract.

2 NaH2PO2 → Na2HPO4 + PH3


Sodium hypophosphite is mainly used for electroless nickel plating. With this method, a durable nickel-phosphorus film can coat objects with irregular surfaces, and can widely be in avionics, aviation and the petroleum field.

Sodium hypophosphite is capable of reducing nickel ions in solution to metallic nickel on metal substrates as well as on plastic substrates.[1] The latter requires that the substrate is activated with fine particles of palladium. The resulting nickel deposit contains up to 15% phosphorus.

It also can be used as a food additive.

DEA List I status[edit]

The United States Drug Enforcement Administration designated sodium hypophosphite as a List I chemical under 21 CFR 1310.02 effective November 17, 2001, specifically mentioning the compound together with several other salts of hypophosphorous acid.[2][3]


  1. ^ D. Rich & M. Smith, Electroless Deposition of Nickel, Cobalt and Iron, IBM Corp (1971)
  2. ^ 66 FR 52670—52675. 17 October 2001.
  3. ^ 37 CFR 1310.02