Substance profile
Hydrofluoric acid
Hydrofluoric acid is a colorless gas, fumes in air with a strong, irritating odor.
01 · Identification
What Hydrofluoric acid is
Hydrofluoric acid is a colorless gas, fumes in air with a strong, irritating odor. Its molecular formula is FH and its molecular weight is 20.006 g/mol. It boils at 19.4 °C, melts at -83.6 °C, is miscible with water.
Under the GHS it carries the signal word Danger. It is classed as hazardous Air Pollutants (HAPs).
02 · Identifiers
Hydrofluoric acid identifiers and molecular data
Hydrofluoric acid CAS number and EC number
Hydrofluoric acid molecular formula and molecular weight
Other names for Hydrofluoric acid
- hydrogen fluoride
- HF
- Anhydrous Hydrofluoric Acid
- Anhydrous Hydrogen Fluoride
- Aqueous Hydrogen Fluoride (I.E., Hydrofluoric Acid)
- Fluorhydric Acid
- Fluoric Acid
- Fluorine Hydride (Fh)
- Fluorine Monohydride
- Hf-A
- Hydrofluoric Acid Gas
- Hydrofluoric Acid, Anhydrous
- Hydrogen Fluoride (Anhydrous)
- Hydrogen Fluoride (Hf)
- Alsurf 45
- Antisal 2B
03 · GHS classification
Hydrofluoric acid hazard classification
Harmonised classification under CLP Annex VI. This is the legally binding classification in the EU; other jurisdictions may differ.
Hydrofluoric acid pictograms and signal word
Hydrofluoric acid hazard class and category
| Hazard class | Category | From code | Pictogram |
|---|---|---|---|
| Acute toxicity - oral GHS chapter 3.1 | Category 1 or 2 | H300 | GHS06 |
| Acute toxicity - dermal GHS chapter 3.1 | Category 1 or 2 | H310 | GHS06 |
| Acute toxicity - inhalation GHS chapter 3.1 | Category 1 or 2 | H330 | 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.
Hydrofluoric acid hazard statements (H-codes)
| Code | Hazard statement |
|---|---|
| H310 | Fatal in contact with skin. |
| H330 | Fatal if inhaled. |
| H300 | Fatal if swallowed. |
| H314 | Causes severe skin burns and eye damage. |
This page lists only the codes assigned to Hydrofluoric 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 Hydrofluoric acid
Our own Hydrofluoric 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
Hydrofluoric acid precautionary statements
CLP Annex VI assigns 11 precautionary statements to Hydrofluoric 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
Hydrofluoric 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 флуорид |
| Spanish español | Fluoruro de hidrógeno |
| Czech čeština | fluorovodík |
| Danish dansk | hydrogenfluorid |
| German Deutsch | Fluorwasserstoff Hydrogenfluorid |
| Estonian eesti | vesinikfluoriid |
| Greek ελληνικά | υδροφθόριο |
| English English | hydrogen fluoride |
| French français | fluorure d'hydrogène |
| Croatian hrvatski | fluorovodik |
| Italian italiano | acido fluoridrico |
| Latvian latviešu | fluorūdeņradis |
| Lithuanian lietuvių | vandenilio fluoridas |
| Hungarian magyar | hidrogén-fluorid |
| Maltese Malti | fluworur tal-idroġenu |
| Dutch Nederlands | waterstoffluoride |
| Polish polski | fluorowodór |
| Portuguese português | fluoreto de hidrogénio |
| Romanian română | acid fluorhidric |
| Slovak slovenčina | fluorovodík |
| Slovenian slovenščina | vodikov fluorid |
| Finnish suomi | fluorivety |
| Swedish svenska | vätefluorid |
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
Hydrofluoric acid GHS label elements
Everything CLP Annex VI fixes for Hydrofluoric acid, laid out the way it appears on a label. The greyed lines are the parts only the supplier can fill in.
Danger
Hydrofluoric acid
- Fatal in contact with skin.
- Fatal if inhaled.
- Fatal if swallowed.
- Causes severe skin burns and eye damage.
- Do not breathe dust/fume/gas/mist/vapours/spray.
- Do not eat, drink or smoke when using this product.
- Use only outdoors or in a well-ventilated area.
- Wear protective gloves/protective clothing/eye protection/face protection/hearing protection/…
- IF SWALLOWED:
- IF ON SKIN:
- IF INHALED:
- Immediately call a POISON CENTER/doctor/…
- Rinse mouth.
- Do NOT induce vomiting.
- Wash with plenty of water/…
Supplier name, address and telephone number· Product identifier·Nominal quantity
Need this as an actual label? Open Hydrofluoric acid in the GHS label constructor →
07 · Health hazards
Hydrofluoric acid health hazards and exposure limits
Hydrofluoric acid hazard summary
Hydrogen fluoride is a colorless, fuming liquid or gas with a strong, irritating odor. It is usually shipped in steel cylinders as a compressed gas. Hydrogen fluoride readily dissolves in water to form colorless hydrofluoric acid solutions; dilute solutions are visibly indistinguishable from water.
Source: Agency for Toxic Substances and Disease Registry (ATSDR)
Hydrofluoric acid occupational exposure limits
| Limit | Value | Source |
|---|---|---|
| PEL | 3.0 [ppm], as F | Haz-Map, Information on Hazardous Chemicals and Occupational Diseases |
| PEL | 3 ppm (2 mg/m³) | Occupational Safety and Health Administration (OSHA) |
| PEL | TWA 3 ppm See Appendix G | The National Institute for Occupational Safety and Health (NIOSH) |
| REL | 3 ppm (2 mg/m³) | Occupational Safety and Health Administration (OSHA) |
| REL | 6 ppm (5 mg/m³) [15 minutes] | Occupational Safety and Health Administration (OSHA) |
| REL | TWA 3 ppm (2.5 mg/m3) C 6 ppm (5 mg/m3) [15-minute] | The National Institute for Occupational Safety and Health (NIOSH) |
| IDLH | 30 ppm [From NPG: Hydrogen fluoride] (NIOSH, 2024) | CAMEO Chemicals |
| IDLH | 30 ppm (NIOSH, 2024) | CAMEO Chemicals |
| IDLH | 30.0 [ppm], as F | 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
Hydrofluoric 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.
Hydrofluoric acid boiling point
| Property | Value | Conditions | Source |
|---|---|---|---|
| Boiling point | 19.44 °C (67 °F) | NIOSH | |
| 66.67 °C (152 °F) | at 760 mmHg | CAMEO | |
| 19.5 °C (67.1 °F) | at 760 mmHg | CAMEO |
Hydrofluoric acid melting point
| Property | Value | Conditions | Source |
|---|---|---|---|
| Melting point | -83.57 °C (-118.4 °F) | HSDB | |
| -83.33 °C (-118 °F) | NIOSH | ||
| -69 °C (-92.2 °F) | CAMEO |
Hydrofluoric acid density
| Property | Value | Conditions | Source |
|---|---|---|---|
| Density | 1.23 g/cm³ | CAMEO | |
| 0.991 g/cm³ | at 19.5 °C | CAMEO | |
| 1 g/cm³ | at 19.44 °C | NIOSH |
Hydrofluoric acid solubility
| Property | Value | Conditions | Source |
|---|---|---|---|
| Solubility | Miscible with water | HSDB | |
| Very soluble in water | HSDB | ||
| Very soluble in alcohol, slightly soluble in ether, soluble in many organic solvents | HSDB |
Hydrofluoric acid vapor pressure
| Property | Value | Conditions | Source |
|---|---|---|---|
| Vapor pressure | 783 mmHg | NIOSH | |
| 917 mmHg | at 25 °C | HSDB | |
| 150 mmHg | at 25 °C, partial pressure for 70% solution | CAMEO |
Hydrofluoric acid flash point
| Property | Value | Conditions | Source |
|---|---|---|---|
| Flash point | Not Flammable (EPA, 1998) | CAMEO |
Hydrofluoric acid autoignition temperature
| Property | Value | Conditions | Source |
|---|---|---|---|
| Autoignition temperature | Not flammable (USCG, 1999) | CAMEO |
Hydrofluoric acid lower explosive limit (LEL)
| Property | Value | Conditions | Source |
|---|---|---|---|
| Lower explosive limit (LEL) | Nonflammable Gas | NIOSH | |
| Non-Flammable (EPA, 1998) | CAMEO |
Hydrofluoric acid upper explosive limit (UEL)
| Property | Value | Conditions | Source |
|---|---|---|---|
| Upper explosive limit (UEL) | Non-Flammable (EPA, 1998) | CAMEO |
Hydrofluoric acid vapor density
| Property | Value | Conditions | Source |
|---|---|---|---|
| Vapor density | 0.7 (air = 1) | CAMEO | |
| 1.86 (air = 1) | at 25 °C | CAMEO |
Hydrofluoric acid odor threshold
| Property | Value | Conditions | Source |
|---|---|---|---|
| Odor threshold | Odor ... is detectable in air @ 0.5 to 3 ppm. | HSDB | |
| Odor low 0.0333 mg/cu m; Odor high 0.1333 mg/cu m; Irritating concn 4.17 mg/cu m. | HSDB | ||
| Odor Threshold Low: 0.04 [ppm] | Haz-Map |
Hydrofluoric acid critical temperature and pressure
| Property | Value | Conditions | Source |
|---|---|---|---|
| Critical temperature and pressure | 188 °C (370.4 °F) | HSDB |
Hydrofluoric acid corrosivity
| Property | Value | Conditions | Source |
|---|---|---|---|
| Corrosivity | Corrosive, dissolves silica, silicic acid, glass | HSDB |
Values compiled from PubChem Laboratory Chemical Safety Summary. Temperatures converted to Fahrenheit for reference.
09 · Handling and storage
Hydrofluoric acid storage and handling
Hydrofluoric acid reactive group
CAMEO Chemicals places Hydrofluoric acid in the reactive groups Acids, Weak, Fluoride Salts, Soluble, 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.
Hydrofluoric acid safe storage
Cool. Well closed. Fireproof if in building. Ventilation along the floor. Separated from food and feedstuffs and incompatible materials. Store in an area without drain or sewer access. See Chemical Dangers.
Source: ILO-WHO International Chemical Safety Cards (ICSCs)
Hydrofluoric acid storage conditions
Hydrogen fluoride should be stored in cool, dry, well ventilated areas out of the direct rays of the sun.
Source: Hazardous Substances Data Bank (HSDB)
Hydrofluoric acid incompatible materials
Metals, water or steam. [Note: Corrosive to metals. Will attack glass and concrete].
Source: Hazardous Substances Data Bank (HSDB)
Hydrofluoric acid reactivity
Mixing in equal molar portions with any of the following substances in a closed container caused the temperature and pressure to increase: acetic anhydride, 2-aminoethanol, chlorosulfonic acid, aqueous ammonia (48.7%), ethylenediamine, ethyleneimine, oleum, aqueous sulfuric acid (48.7%), aqueous sodium hydroxide (48.7%), propylene oxide, vinyl acetate [NFPA 1991].
Source: CAMEO Chemicals
Planning storage for a mix of chemicals? Check Hydrofluoric acid in the storage compatibility matrix →
10 · Transport
Hydrofluoric 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.
Hydrofluoric acid under UN 1052 — 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 FLUORIDE, ANHYDROUS | 8 | CT1 | I | |
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) |
|---|---|---|---|
| Hydrogen fluoride, anhydrous | 8 | I | |
Source: 49 CFR 172.101 Hazardous Materials Table · eCFR, revision 2026-08-03. Class 8 is “Corrosive material” (49 CFR 173.2).
11 · Questions
Hydrofluoric acid — frequently asked questions
What is the CAS number of Hydrofluoric acid?
The CAS number of Hydrofluoric acid is 7664-39-3. Its EC number is 231-634-8.
What is the chemical formula of Hydrofluoric acid?
The molecular formula of Hydrofluoric acid is FH and its molecular weight is 20.006 g/mol.
What does a Hydrofluoric acid label have to show?
Under CLP Annex VI the label for Hydrofluoric acid carries the pictograms Skull and crossbones and Corrosion and the signal word is Danger.
Is Hydrofluoric acid flammable?
CLP Annex VI assigns Hydrofluoric 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. The flash point reported for it is Not Flammable (EPA, 1998) (CAMEO).
Is Hydrofluoric acid a carcinogen?
CLP Annex VI records no harmonised carcinogenicity classification for Hydrofluoric 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.
What is the exposure limit for Hydrofluoric acid?
The US occupational exposure limit reported for Hydrofluoric acid is 3.0 [ppm], as F (Haz-Map, Information on Hazardous Chemicals and Occupational Diseases). 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 Hydrofluoric acid?
The boiling point reported for Hydrofluoric acid is 19.44 °C (67 °F) (NIOSH).
What is the melting point of Hydrofluoric acid?
The melting point reported for Hydrofluoric acid is -83.57 °C (-118.4 °F) (HSDB).
How should Hydrofluoric acid be stored?
Hydrogen fluoride should be stored in cool, dry, well ventilated areas out of the direct rays of the sun. (Hazardous Substances Data Bank (HSDB))
Nearby
Substances next to Hydrofluoric acid
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