Substance profile
Hydrochloric acid
Hydrochloric acid is a colorless gas with a pungent, irritating odor.
01 · Identification
What Hydrochloric acid is
Hydrochloric acid is a colorless gas with a pungent, irritating odor. It boils at -85 °C, melts at -114 °C.
Under the GHS it carries the signal word Danger. It is classed as hazardous Air Pollutants (HAPs).
02 · Identifiers
Hydrochloric acid identifiers and molecular data
Hydrochloric acid CAS number and EC number
Hydrochloric acid molecular formula and molecular weight
Other names for Hydrochloric acid
- muriatic acid
- hydrogen chloride solution
- HCl
- Anhydrous Hydrochloric Acid
- Anhydrous Hydrogen Chloride
- Chlorohydric Acid
- Hydrochloric Acid (Aerosol Forms Only)
- Hydrochloric Acid Gas
- Hydrochloric Acid, Anhydrous
- Hydrochloric Acid, Trimer
- Hydrogen Chloride
- Hydrogen Chloride (Anhydrous)
- Hydrogen Chloride (Gas Only)
- Hydrogen Chloride (Hydrochloric Acid)
- Hydrogen Chloride Dimer
- hydrogen chloride
03 · GHS classification
Hydrochloric acid hazard classification
Harmonised classification under CLP Annex VI. This is the legally binding classification in the EU; other jurisdictions may differ.
Hydrochloric acid pictograms and signal word
Hydrochloric acid hazard class and category
| Hazard class | Category | From code | Pictogram |
|---|---|---|---|
| Acute toxicity - inhalation GHS chapter 3.1 | Category 3 | H331 | GHS06 |
| Skin corrosion/irritation GHS chapter 3.2 | Category 1A or 1B or 1C | H314 | GHS05 |
Where two values are shown with “or”, the hazard statement is shared by more than one category or by more than one class, and the code alone does not say which. H272, for example, belongs to oxidising liquids and to oxidising solids — the physical state decides. The binding answer for a specific entry is in the CLP Annex VI table itself.
Hydrochloric acid hazard statements (H-codes)
| Code | Hazard statement |
|---|---|
| H331 | Toxic if inhaled. |
| H314 | Causes severe skin burns and eye damage. |
This page lists only the codes assigned to Hydrochloric acid. The full reference lives on the hazard statements hub, the precautionary statements hub and the GHS pictograms hub.
Safety Data Sheet
Getting an SDS for Hydrochloric acid
Our own Hydrochloric acid safety data sheet walks through all sixteen sections of the published data. What it is not is the document an inspector asks for: an SDS is issued for a product by its supplier, so the sheet covering the grade actually standing in your store exists only in that supplier’s version. Collecting those and keeping them current as suppliers revise them is a separate job.
04 · Precautionary statements
Hydrochloric acid precautionary statements
CLP Annex VI assigns 7 precautionary statements to Hydrochloric acid. They are grouped the way a label groups them: what to do before handling, what to do when something has already happened, how to store it and how to dispose of it.
Prevention
What to do before and during handling so the hazard never happens.
Response
What to do once exposure, spillage or fire has already happened.
Reading the notation. … is a blank the supplier fills in — not a truncated sentence.· [square brackets] mark a part printed only when it applies.
05 · Names in the regulation
Hydrochloric acid name in 23 EU languages
CLP Annex VI Part 3 is published in every language edition of the regulation, and the identification column is written out in each of them. Nothing below is translated by us: each line is the name as that edition prints it. Under Art. 18(2) the substance name from Annex VI is a lawful product identifier, so this is the wording to put on a label going to that market — and where the cell lists several designations, any one of them qualifies.
| Language | Name in CLP Annex VI Part 3 |
|---|---|
| Bulgarian български | водороден хлорид |
| Spanish español | Cloruro de hidrógeno |
| Czech čeština | chlorovodík |
| Danish dansk | hydrogenchlorid |
| German Deutsch | Hydrogenchlorid Chlorwasserstoff |
| Estonian eesti | vesinikkloriid |
| Greek ελληνικά | υδροχλώριο |
| English English | hydrogen chloride |
| French français | chlorure d'hydrogène |
| Croatian hrvatski | klorovodik |
| Italian italiano | cloruro di idrogeno |
| Latvian latviešu | hlorūdeņradis |
| Lithuanian lietuvių | vandenilio chloridas |
| Hungarian magyar | hidrogén-klorid (gáz) |
| Maltese Malti | klorur tal-idroġenu |
| Dutch Nederlands | waterstofchloride |
| Polish polski | chlorowodór |
| Portuguese português | cloreto de hidrogénio |
| Romanian română | clorură de hidrogen |
| Slovak slovenčina | chlorovodík |
| Slovenian slovenščina | vodikov klorid |
| Finnish suomi | kloorivety |
| Swedish svenska | väteklorid |
All 23 language editions of Annex VI carry this entry. Irish is the twenty-fourth official EU language and has no line here for a different reason: no consolidated CLP text has ever been published in Irish, so there is no Irish edition of Annex VI to quote a name from. Source: consolidated CLP, CELEX 02008R1272, language editions. © European Union, https://eur-lex.europa.eu — only the electronic Official Journal of the European Union is authentic.
06 · Label elements
Hydrochloric acid GHS label elements
Everything CLP Annex VI fixes for Hydrochloric acid, laid out the way it appears on a label. The greyed lines are the parts only the supplier can fill in.
Danger
Hydrochloric acid
- Toxic if inhaled.
- Causes severe skin burns and eye damage.
- Do not breathe dust/fume/gas/mist/vapours/spray.
- Use only outdoors or in a well-ventilated area.
- Wear protective gloves/protective clothing/eye protection/face protection/hearing protection/…
- IF SWALLOWED:
- IF INHALED:
- Immediately call a POISON CENTER/doctor/…
- Do NOT induce vomiting.
Supplier name, address and telephone number· Product identifier·Nominal quantity
Need this as an actual label? Open Hydrochloric acid in the GHS label constructor →
07 · Health hazards
Hydrochloric acid health hazards and exposure limits
Hydrochloric acid hazard summary
At room temperature, hydrogen chloride is a colorless to slightly yellow, corrosive, nonflammable gas that is heavier than air and has a strong irritating odor. On exposure to air, hydrogen chloride forms dense white corrosive vapors. Hydrogen chloride can be released from volcanoes. Hydrogen chloride has many uses, including cleaning, pickling, electroplating metals, tanning leather, and refining and producing a wide variety of products. Hydrogen chloride can be formed during the burning of many plastics. Upon contact with water, it forms hydrochloric acid. Both hydrogen chloride and hydrochloric acid are corrosive.
Source: Agency for Toxic Substances and Disease Registry (ATSDR)
Hydrochloric acid carcinogenicity classification
Evaluation: There is inadequate evidence for the carcinogenicity in humans of hydrochloric acid. There is inadequate evidence for the carcinogenicity in experimental animals of hydrochloric acid. Overall evaluation: Hydrochloric acid is not classifiable as to its carcinogenicity to humans (Group 3).
Source: Hazardous Substances Data Bank (HSDB)
An IARC group and a CLP classification answer different questions. IARC judges whether the evidence for cancer in humans is strong enough; CLP Annex VI is the legally binding EU classification. A substance can carry one and not the other.
Hydrochloric acid occupational exposure limits
| Limit | Value | Source |
|---|---|---|
| PEL | 5 ppm (7 mg/m³) | Occupational Safety and Health Administration (OSHA) |
| PEL | C 5 ppm (7 mg/m3) | The National Institute for Occupational Safety and Health (NIOSH) |
| REL | 5 ppm (7 mg/m³) | Occupational Safety and Health Administration (OSHA) |
| REL | C 5 ppm (7 mg/m3) | The National Institute for Occupational Safety and Health (NIOSH) |
| IDLH | 50 ppm [From NPG: Hydrogen chloride] (NIOSH, 2024) | CAMEO Chemicals |
| IDLH | 50 ppm (NIOSH, 2024) | CAMEO Chemicals |
| IDLH | 50.0 [ppm] | Haz-Map, Information on Hazardous Chemicals and Occupational Diseases |
These are United States values. The European Union sets its own indicative and binding limits, and the figure that applies at a given workplace is the one in the local regulation — not the one shown here.
08 · Physical and chemical properties
Hydrochloric acid properties
Every value is shown with the conditions it was measured under and the source it came from. Where sources disagree, all values are listed rather than one being picked — the difference is usually a different form of the substance, not an error.
Hydrochloric acid boiling point
| Property | Value | Conditions | Source |
|---|---|---|---|
| Boiling point | -85.05 °C (-121.1 °F) | at 760 mmHg | HSDB |
| -85 °C (-121 °F) | NIOSH | ||
| 50.56 °C (123 °F) | at 760 mmHg | CAMEO |
Hydrochloric acid melting point
| Property | Value | Conditions | Source |
|---|---|---|---|
| Melting point | -114.22 °C (-173.6 °F) | HSDB | |
| -114.44 °C (-174 °F) | NIOSH | ||
| -114.78 °C (-174.6 °F) | CAMEO |
Hydrochloric acid density
| Property | Value | Conditions | Source |
|---|---|---|---|
| Density | 0.0016 g/cm³ | HSDB | |
| 0.001 g/cm³ | ICSC | ||
| 1.49 g/cm³ | at 25 °C | DOE PAC |
Hydrochloric acid solubility
| Property | Value | Conditions | Source |
|---|---|---|---|
| Solubility | (86 °F): 67% | at 30 °C | NIOSH |
| 67 % at 86 °F (NIOSH, 2024) | at 30 °C | CAMEO | |
| Solubility in water, g/100ml at 30 °C: 67 (moderate) | at 30 °C | ICSC |
Hydrochloric acid vapor pressure
| Property | Value | Conditions | Source |
|---|---|---|---|
| Vapor pressure | 30780 mmHg | NIOSH | |
| 413.6 mmHg | CAMEO | ||
| 35420 mmHg | at 25 °C | HSDB |
Hydrochloric acid autoignition temperature
| Property | Value | Conditions | Source |
|---|---|---|---|
| Autoignition temperature | Not flammable (USCG, 1999) | CAMEO |
Hydrochloric acid lower explosive limit (LEL)
| Property | Value | Conditions | Source |
|---|---|---|---|
| Lower explosive limit (LEL) | Behavior in fire: Pressurized container may explode and release toxic, irritating vapors. | HSDB | |
| Nonflammable Gas | NIOSH | ||
| Not combustible. (EPA, 1998) | CAMEO |
Hydrochloric acid upper explosive limit (UEL)
| Property | Value | Conditions | Source |
|---|---|---|---|
| Upper explosive limit (UEL) | Not combustible. (EPA, 1998) | CAMEO |
Hydrochloric acid vapor density
| Property | Value | Conditions | Source |
|---|---|---|---|
| Vapor density | 1.268 (air = 1) | Air = 1.000 | HSDB |
| 1.268 (air = 1) | CAMEO | ||
| 1.27 (air = 1) | CAMEO |
Hydrochloric acid odor threshold
| Property | Value | Conditions | Source |
|---|---|---|---|
| Odor threshold | Air: 0.77 uL/L; Odor safety class C; C= less than 50% of distracted persons perceive warning of TLV. | HSDB | |
| Odor low: 7.0 mg/cu m; Odor high: 49.0 mg/cu m; strong irritating odor; Irritating concn= 49.00 mg/cu m. | HSDB | ||
| Low threshold= 0.26 ppm. High threshold= 0.3 ppm. | HSDB |
Hydrochloric acid critical temperature and pressure
| Property | Value | Conditions | Source |
|---|---|---|---|
| Critical temperature and pressure | 51.4 °C (124.5 °F) | HSDB |
Hydrochloric acid corrosivity
| Property | Value | Conditions | Source |
|---|---|---|---|
| Corrosivity | Corrosive | HSDB |
Values compiled from PubChem Laboratory Chemical Safety Summary. Temperatures converted to Fahrenheit for reference.
09 · Handling and storage
Hydrochloric acid storage and handling
Hydrochloric acid reactive group
CAMEO Chemicals places Hydrochloric acid in the reactive groups Acids, Strong Non-oxidizing, Water and Aqueous Solutions. Compatibility with other chemicals is worked out from the group, not from the individual substance — which is why two substances you have never seen react can still be flagged as a pair that must be separated.
A reactive group is a CAMEO Chemicals (US NOAA) grouping, not a GHS hazard class: it has no code, no category and no legal force. It is what the storage compatibility matrix on this site computes from.
Hydrochloric acid safe storage
Cool. Fireproof if in building. Separated from food and feedstuffs and incompatible materials. See Chemical Dangers. Keep in a well-ventilated room.
Source: ILO-WHO International Chemical Safety Cards (ICSCs)
Hydrochloric acid storage conditions
Keep container tightly closed in a dry and well-ventilated place. Storage class (TRGS 510): Gases
Source: Hazardous Substances Data Bank (HSDB)
Hydrochloric acid incompatible materials
The aqueous solution is a strong acid. Corrosive fumes emitted on contact with air. Reacts violently with bases, oxidizers forming toxic chlorine gas. Reacts, often violently, with acetic anhydride, active metals, aliphatic amines, alkanolamines, alkylene oxides, aromatic amines, amides, 2-aminoethanol, ammonia, ammonium hydroxide, calcium phosphide, chlorosulfonic acid, ethylene diamine, ethyleneimine, epichlorohydrin, isocyanates, metal acetylides, oleum, organic anhydrides, perchloric acid, 3-propiolactone, uranium phosphide, sulfuric acid, vinyl acetate, vinylidene fluoride. Highly corrosive to most metals, forming flammable hydrogen gas. Attacks some plastics, rubber, and coatings.
Source: Hazardous Substances Data Bank (HSDB)
Planning storage for a mix of chemicals? Check Hydrochloric acid in the storage compatibility matrix →
10 · Transport
Hydrochloric acid UN number and transport classification
Transport classification is a separate system from the GHS classification above. It decides how a package is marked and how a load may be carried; it does not follow from the workplace label, and the workplace label does not follow from it. The entries below are linked by CAS number, never by name.
The same CAS number is shipped under more than one UN number. Which entry applies follows from the form and the concentration of the consignment — read the proper shipping name, not the CAS.
Hydrochloric acid under UN 1050 — shipping name, class and packing group
Europe · ADR 2025, Table A
| Proper shipping name (3.1.2) | Class | Classification code | PG | Labels (column 5) |
|---|---|---|---|---|
| HYDROGEN CHLORIDE, ANHYDROUS | 2 | 2TC | — | |
Source: ADR 2025, Table A of Chapter 3.2 · ECE/TRANS/352 Vol. I (UNECE). Class 2 is “Gases” (ADR 2.1.1.1).
United States · 49 CFR 172.101 Hazardous Materials Table
| Proper shipping name (column 2) | Class or division | PG | Labels (column 6) |
|---|---|---|---|
| Hydrogen chloride, anhydrous | 2.3 | — | |
Source: 49 CFR 172.101 Hazardous Materials Table · eCFR, revision 2026-08-03. Class 2.3 is “Poisonous gas” (49 CFR 173.2).
Hydrochloric acid under UN 1789 — shipping name, class and packing group
Europe · ADR 2025, Table A
| Proper shipping name (3.1.2) | Class | Classification code | PG | Labels (column 5) |
|---|---|---|---|---|
| HYDROCHLORIC ACID | 8 | C1 | II | |
| HYDROCHLORIC ACID | 8 | C1 | III | |
Source: ADR 2025, Table A of Chapter 3.2 · ECE/TRANS/352 Vol. I (UNECE). Class 8 is “Corrosive substances” (ADR 2.1.1.1).
United States · 49 CFR 172.101 Hazardous Materials Table
| Proper shipping name (column 2) | Class or division | PG | Labels (column 6) |
|---|---|---|---|
| Hydrochloric acid | 8 | II | |
| Hydrochloric acid | 8 | III | |
Source: 49 CFR 172.101 Hazardous Materials Table · eCFR, revision 2026-08-03. Class 8 is “Corrosive material” (49 CFR 173.2).
Hydrochloric acid under UN 2186 — shipping name, class and packing group
Europe · ADR 2025, Table A
| Proper shipping name (3.1.2) | Class | Classification code | PG | Labels (column 5) |
|---|---|---|---|---|
| HYDROGEN CHLORIDE, REFRIGERATED LIQUID | 2 | 3TC | — | — |
Not accepted for carriage under ADR. ADR 2.2.2.2.2 — this substance is not accepted for carriage under ADR. This says nothing about the United States: check the 49 CFR panel separately.
Source: ADR 2025, Table A of Chapter 3.2 · ECE/TRANS/352 Vol. I (UNECE). Class 2 is “Gases” (ADR 2.1.1.1).
United States · 49 CFR 172.101 Hazardous Materials Table
| Proper shipping name (column 2) | Class or division | PG | Labels (column 6) |
|---|---|---|---|
| Hydrogen chloride, refrigerated liquid | 2.3 | — | |
Source: 49 CFR 172.101 Hazardous Materials Table · eCFR, revision 2026-08-03. Class 2.3 is “Poisonous gas” (49 CFR 173.2).
11 · Questions
Hydrochloric acid — frequently asked questions
What is the CAS number of Hydrochloric acid?
The CAS number of Hydrochloric acid is 7647-01-0. Its EC number is 231-595-7.
What does a Hydrochloric acid label have to show?
Under CLP Annex VI the label for Hydrochloric acid carries the pictograms Gas cylinder, Skull and crossbones and Corrosion and the signal word is Danger.
Is Hydrochloric acid flammable?
CLP Annex VI assigns Hydrochloric acid no flammability hazard class. That is not a statement that it cannot burn: the harmonised list only records the hazards that were assessed for it.
Is Hydrochloric acid a carcinogen?
CLP Annex VI records no harmonised carcinogenicity classification for Hydrochloric acid. Annex VI is a list of agreed classifications, not a list of substances found safe, so this is an absence of a classification rather than a clean bill of health. IARC places it in Group 3: not classifiable as to its carcinogenicity to humans.
What is the exposure limit for Hydrochloric acid?
The US occupational exposure limit reported for Hydrochloric acid is 5 ppm (7 mg/m³) (Occupational Safety and Health Administration (OSHA)). Limits differ by country: the EU sets its own indicative and binding values, and the figure that applies at a given workplace is the one in the local regulation.
What is the boiling point of Hydrochloric acid?
The boiling point reported for Hydrochloric acid is -85.05 °C (-121.1 °F), at 760 mmHg (HSDB).
What is the melting point of Hydrochloric acid?
The melting point reported for Hydrochloric acid is -114.22 °C (-173.6 °F) (HSDB).
How should Hydrochloric acid be stored?
Keep container tightly closed in a dry and well-ventilated place. Storage class (TRGS 510): Gases (Hazardous Substances Data Bank (HSDB))
Nearby
Substances next to Hydrochloric acid
Keep going: substances starting with H, or search the whole database by name, CAS number, pictogram or signal word.
Next