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Inorganic acids

Nitrous acid

Also known as Nitrosyl hydroxide, Kyselina dusite, dioxonitric acid

CAS 7782-77-6Formula HNO2Molar mass 47.01 g/molEC 231-963-7
GHS signal word: Danger. Pictograms: Corrosive, Acute toxicity (severe), Hazardous to the environment 8 suppliers listed
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Nitrous acid chemical structure, HNO2, CAS 7782-77-6
2D chemical structure

Key facts

What buyers check first

All properties
CAS number
7782-77-6
Formula
HNO2
Molar mass
47.01 g/mol
EC number
231-963-7
HS code
281119
Category
Inorganic acids

What is Nitrous acid?

Plain description, key identifiers and synonyms

Nitrous acid is a nitrogen oxoacid. It is a conjugate acid of a nitrite.

Identifiers

Registry numbers, names and line notations, tap to copy

IUPAC name
nitrous acid
CAS number
7782-77-6 CAS number cross-checkedOther or deprecated CAS: 14797-65-0
EC number
231-963-7
Molecular formula
HNO2
UNII
T2I5UM75DN
INCI name
NITROUS ACID
InChIKey
IOVCWXUNBOPUCH-UHFFFAOYSA-N
InChI
InChI=1S/HNO2/c2-1-3/h(H,2,3)
SMILES (canonical and isomeric)
N(=O)O

Synonyms

  • Nitrosyl hydroxide
  • Kyselina dusite
  • dioxonitric acid
  • hydroxidooxidonitrogen
  • Acid, Nitrous
  • hydrogen dioxonitrate(1-)
  • (NO(OH))
  • [NO(OH)]
  • HONO
  • Nitrogen dioxide ion
  • Nitrous acid, trans
  • Nitrogen peroxide ion

Physical and chemical properties

Measured values and descriptors computed from the structure

Physical and chemical properties

Measured values, check the supplier specification for your grade

No measured properties are recorded for this substance yet. Ask suppliers for a technical data sheet.

Values vary by grade. Ask suppliers for the COA or TDS of the batch you buy.

Computed descriptors

Calculated from the structure, useful for screening and formulation

Molecular weight
47.01 g/molcalc.
Exact mass
47.0007 Dacalc.
LogP (octanol/water)
0.14calc.
Topological polar surface area
49.66 Ųcalc.
Hydrogen bond donors
1calc.
Hydrogen bond acceptors
2calc.
Rotatable bonds
0calc.
Heavy atoms
3calc.
Rings
0calc.
Aromatic rings
0calc.
Fraction sp3 carbons
0calc.
Formal charge
0calc.
Stereocentres
0calc.

Calculated for screening. Confirm critical figures with the supplier.

Safety and hazards

GHS classification summary, not a safety data sheet

GHS signal word
Danger
GHS05: Corrosive
Corrosive
GHS06: Acute toxicity (severe)
Acute toxicity (severe)
GHS09: Hazardous to the environment
Hazardous to the environment

Hazard statements

  • H300Fatal if swallowed.
  • H314Causes severe skin burns and eye damage.
  • H318Causes serious eye damage.
  • H400Very toxic to aquatic life.
Precautionary statements (19)
  • P260Do not breathe dust, fume, gas, mist, vapours or spray.
  • P264Wash skin thoroughly after handling.
  • P264 + P265Wash skin thoroughly after handling. Do not touch eyes.
  • P270Do not eat, drink or smoke when using this product.
  • P273Avoid release to the environment.
  • P280Wear protective gloves, protective clothing, eye protection and face protection.
  • P301 + P316If swallowed: Get emergency medical help immediately.
  • P301 + P330 + P331If swallowed: Rinse mouth. Do not induce vomiting.
  • P302 + P361 + P354If on skin: Take off immediately all contaminated clothing. Immediately rinse with water for several minutes.
  • P304 + P340If inhaled: Remove person to fresh air and keep comfortable for breathing.
  • P305 + P354 + P338If in eyes: Immediately rinse with water for several minutes. Remove contact lenses, if present and easy to do. Continue rinsing.
  • P316Get emergency medical help immediately.
  • P317Get medical help.
  • P321Specific treatment (see supplemental first aid instructions on the label).
  • P330Rinse mouth.
  • P363Wash contaminated clothing before reuse.
  • P391Collect spillage.
  • P405Store locked up.
  • P501Dispose of contents and container in accordance with local regulations.

GHS classification summary, not a safety data sheet (SDS). Classifications can differ by supplier, grade and concentration. Always check the supplier's SDS.

Full safety data and first aid

Nitrous acid suppliers

Sponsored listings first, then the documented ranking: membership, verification, replies, completeness, freshness and ratings

All 8 suppliers
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Where suppliers are based

8 suppliers in 6 countries

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Nitrous acid price

Indicative price range per kg from live supplier offers

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Uses and applications

What the substance is used for, by industry and function

Formation of diazotizing compounds by reaction with primary aromatic amines, source of nitric oxide.

Cosmetic ingredient, INCI name NITROUS ACID(humectant, solvent)

Roles

  • animal metabolite
  • eukaryotic metabolite
  • human metabolite
  • mammalian metabolite
  • metabolite

Cosmetic functions

  • Humectant
  • Solvent

How it is made

Formed by the action of strong acids on inorganic nitrites.

Nitrous acid is not an article of commerce owing to its inherent instability. Sodium nitrite serves as the primary industrial source for nitrous acid in organic syntheses, for instance in the diatozation and nitrosation of aromatic amines. Under controlled conditions of acidification, the nitrous acid generated can react before excessive decomposition occurs.

Regulatory status

Inventories, regulations and trade controls that list this substance

Health and food

  • EU cosmetic ingredient inventory

United States

  • TSCA inventory (USA)
    Status: Active in US commerce

HS code and trade data

Customs classification and reported world trade statistics

Global trade

World import and export statistics for the HS code Nitrous acid is traded under.

HS 2811.19Indicative HS code

Inorganic acids, other than hydrogen fluoride

World exports in 2024
$494M
+6.5% vs 2023, imports $458M
2019 to 2024
Top exporters
  1. China24.9%
  2. Israel16.0%
  3. Jordan * partner reported11.7%
Top importers
  1. China29.3%
  2. United States16.2%
  3. Germany7.0%

* Partner reported figures, a lower bound.

Reported customs values in USD, not prices.Full trade data

The HS code shown for Nitrous acid is indicative (it was assigned by structure rules). Confirm the classification with your customs broker before shipping.

Frequently asked questions

Quick answers about Nitrous acid, based on the data on this page

What is Nitrous acid?

Nitrous acid is a nitrogen oxoacid. It is a conjugate acid of a nitrite.

What is the CAS number of Nitrous acid?

The CAS registry number of Nitrous acid is 7782-77-6. Other or deprecated CAS numbers: 14797-65-0.

What is the molecular formula and weight of Nitrous acid?

The molecular formula of Nitrous acid is HNO2 and its molar mass is 47.01 g/mol.

What is Nitrous acid used for?

Formation of diazotizing compounds by reaction with primary aromatic amines, source of nitric oxide.

Is Nitrous acid hazardous?

Nitrous acid carries the GHS signal word "Danger". Main hazards: fatal if swallowed, causes severe skin burns and eye damage, causes serious eye damage. This summary is not an SDS, always read the supplier safety data sheet.

What is the HS code of Nitrous acid?

Nitrous acid is usually classified under HS code 281119 (II. INORGANIC ACIDS AND INORGANIC OXYGEN COMPOUNDS OF NON-METALS, other). This is indicative, confirm it with your customs broker before shipping.

Where can I buy Nitrous acid?

CompoundList lists 8 suppliers of Nitrous acid in China, India, Germany, United Kingdom and 2 more. Send one free request to get and compare quotes. Your contact details stay private until you accept a quote.

Where can I buy Nitrous acid in India?

2 suppliers in India list Nitrous acid on CompoundList. Filter the suppliers list by country and send a request to compare prices, grades and delivery times.

What is the price of Nitrous acid?

Suppliers quote Nitrous acid on request because prices depend on grade, purity, quantity and destination. A free request on CompoundList gets you several quotes to compare.

Guides for buyers

Practical guides that help when you source, ship or handle Nitrous acid

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Data last updated 7 Oct 2026. Details may have changed, please confirm them with the supplier. Report an error on this page
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