Substance profile
Formic acid
Formic acid is a colorless fuming liquid with a pungent, penetrating odor.
01 · Identification
What Formic acid is
Formic acid is a colorless fuming liquid with a pungent, penetrating odor. Its molecular formula is CH2O2 and its molecular weight is 46.025 g/mol. It boils at 101 °C, melts at 8.3 °C, is miscible with water.
Under the GHS it carries the signal word Danger. It is classed as corrosives.
02 · Identifiers
Formic acid identifiers and molecular data
Formic acid CAS number and EC number
Formic acid molecular formula and molecular weight
Other names for Formic acid
- methanoic acid
- HCOOH
- Add-F
- Ameisensaure
- Aminic Acid
- Bilorin
- Collo-Bueglatt
- Collo-Didax
- Formic Acid (85-95% In Aqueous Solution)
- Formira
- Formisoton
- Formylic Acid
- Hydrogen Carboxylic Acid
- Methanoic Acid Monomer
- formic acid … %
03 · GHS classification
Formic acid hazard classification
Harmonised classification under CLP Annex VI. This is the legally binding classification in the EU; other jurisdictions may differ.
Formic acid pictograms and signal word
Formic acid hazard class and category
| Hazard class | Category | From code | Pictogram |
|---|---|---|---|
| Flammable liquids GHS chapter 2.6 | Category 3 | H226 | GHS02 |
| Corrosive to metals GHS chapter 2.16 | Category 1 | H290 | GHS05 |
| Acute toxicity - oral GHS chapter 3.1 | Category 4 | H302 | GHS07 |
| 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 |
| Serious eye damage/eye irritation GHS chapter 3.3 | Category 1 | H318 | 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.
Formic acid hazard statements (H-codes)
| Code | Hazard statement |
|---|---|
| H226 | Flammable liquid and vapour. |
| H290 | May be corrosive to metals. |
| H331 | Toxic if inhaled. |
| H302 | Harmful if swallowed. |
| H314 | Causes severe skin burns and eye damage. |
| H318 | Causes serious eye damage. |
Formic acid supplemental EU statements (EUH)
| Code | Statement |
|---|---|
| EUH071 | Corrosive to the respiratory tract. |
This page lists only the codes assigned to Formic 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 Formic acid
Our own Formic 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
Formic acid precautionary statements
CLP Annex VI assigns 17 precautionary statements to Formic 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
Formic 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 | мравчена киселина ... % |
| Spanish español | Ácido fórmico ... % |
| Czech čeština | mravenčí kyselina … % |
| Danish dansk | myresyre … % |
| German Deutsch | Ameisensäure % |
| Estonian eesti | sipelghape … % |
| Greek ελληνικά | μυρμηκικό οξύ ... % |
| English English | formic acid … % |
| French français | acide formique à % |
| Croatian hrvatski | mravlja kiselina % |
| Italian italiano | acido formico … % |
| Latvian latviešu | skudrskābe, ... % |
| Lithuanian lietuvių | ... % skruzdžių rūgštis |
| Hungarian magyar | hangyasav … % |
| Maltese Malti | aċidu formiku ... % |
| Dutch Nederlands | mierenzuur … % |
| Polish polski | kwas mrówkowy … % |
| Portuguese português | ácido fórmico a … % |
| Romanian română | acid formic … % |
| Slovak slovenčina | kyselina mravčia … % |
| Slovenian slovenščina | mravljinčna kislina ... % |
| Finnish suomi | muurahaishappo … % |
| Swedish svenska | metansyra % |
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
Formic acid GHS label elements
Everything CLP Annex VI fixes for Formic acid, laid out the way it appears on a label. The greyed lines are the parts only the supplier can fill in.
Danger
Formic acid
- Flammable liquid and vapour.
- May be corrosive to metals.
- Toxic if inhaled.
- Harmful if swallowed.
- Causes severe skin burns and eye damage.
- Causes serious eye damage.
- Corrosive to the respiratory tract.
- Keep away from heat, hot surfaces, sparks, open flames and other ignition sources. No smoking.
- Keep container tightly closed.
- Use explosion-proof [electrical/ventilating/lighting/…] equipment.
- Use only non-sparking tools.
- 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 INHALED:
- IF IN EYES:
- Immediately call a POISON CENTER/doctor/…
- Call a POISON CENTER/doctor/… if you feel unwell.
- Rinse mouth.
- Do NOT induce vomiting.
- Remove contact lenses, if present and easy to do. Continue rinsing.
- Store in a well-ventilated place.
Supplier name, address and telephone number· Product identifier·Nominal quantity
Need this as an actual label? Open Formic acid in the GHS label constructor →
07 · Health hazards
Formic acid health hazards and exposure limits
Formic acid occupational exposure limits
| Limit | Value | Source |
|---|---|---|
| PEL | 5.0 [ppm] | Haz-Map, Information on Hazardous Chemicals and Occupational Diseases |
| PEL | 5 ppm (9 mg/m³) | Occupational Safety and Health Administration (OSHA) |
| PEL | TWA 5 ppm (9 mg/m3) | The National Institute for Occupational Safety and Health (NIOSH) |
| REL | 5 ppm (9 mg/m³) | Occupational Safety and Health Administration (OSHA) |
| REL | TWA 5 ppm (9 mg/m3) | The National Institute for Occupational Safety and Health (NIOSH) |
| IDLH | 30 ppm (NIOSH, 2024) | CAMEO Chemicals |
| IDLH | 30.0 [ppm] | Haz-Map, Information on Hazardous Chemicals and Occupational Diseases |
| IDLH | 30 ppm | Hazardous Substances Data Bank (HSDB) |
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
Formic 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.
Formic acid boiling point
| Property | Value | Conditions | Source |
|---|---|---|---|
| Boiling point | 101 °C (213.8 °F) | HSDB | |
| 106.67 °C (224 °F) | NIOSH | ||
| 100.72 °C (213.3 °F) | at 760 mmHg | CAMEO |
Formic acid melting point
| Property | Value | Conditions | Source |
|---|---|---|---|
| Melting point | 8.3 °C (46.9 °F) | HSDB | |
| -6.67 °C (20 °F) | NIOSH | ||
| 8.39 °C (47.1 °F) | CAMEO |
Formic acid density
| Property | Value | Conditions | Source |
|---|---|---|---|
| Density | 1.22 g/cm³ | NIOSH | |
| 1.22 g/cm³ | at 20 °C | HSDB | |
| 1.2174 g/cm³ | at 20 °C | HSDB |
Formic acid solubility
| Property | Value | Conditions | Source |
|---|---|---|---|
| Solubility | Miscible with ether, acetone, ethyl acetate, methanol, ethanol; partially soluble in benzene, toluene, xylenes | HSDB | |
| Dissolves to the extent of about 10% in benzene, toluene, and xylenes, and to a lesser extent in aliphatic hydrocarbons. | HSDB | ||
| Miscible with water | HSDB |
Formic acid vapor pressure
| Property | Value | Conditions | Source |
|---|---|---|---|
| Vapor pressure | 35 mmHg | NIOSH | |
| 35 mmHg | at 20 °C | CAMEO | |
| 42.59 mmHg | at 25 °C, Extrapolated | HSDB |
Formic acid flash point
| Property | Value | Conditions | Source |
|---|---|---|---|
| Flash point | 68.89 °C (156 °F) | HSDB | |
| 58.89 °C (138 °F) | HSDB | ||
| 50 °C (122 °F) | NIOSH |
Formic acid autoignition temperature
| Property | Value | Conditions | Source |
|---|---|---|---|
| Autoignition temperature | 540 °C (1004 °F) | HSDB | |
| 601.11 °C (1114 °F) | CAMEO | ||
| 520 °C (968 °F) | ICSC |
Formic acid lower explosive limit (LEL)
| Property | Value | Conditions | Source |
|---|---|---|---|
| Lower explosive limit (LEL) | 18 % by volume | HSDB |
Formic acid upper explosive limit (UEL)
| Property | Value | Conditions | Source |
|---|---|---|---|
| Upper explosive limit (UEL) | 57 % by volume | HSDB |
Formic acid vapor density
| Property | Value | Conditions | Source |
|---|---|---|---|
| Vapor density | 1.59 (air = 1) | HSDB | |
| 1.6 (air = 1) | CAMEO |
Formic acid odor threshold
| Property | Value | Conditions | Source |
|---|---|---|---|
| Odor threshold | Water: 1700 mg/L; air 49 uL/L; Odor safety class E. E= less than 10% of attentive persons can detect TLV concentration in the air. | HSDB | |
| Detection threshold: 4.50x10+2 mg/L (liq) and 4.50x10-1 mg/L (gas) | Purity not specified | HSDB | |
| Detection threshold: 6.25x10-1 ppm, 6.25x10-2 ppm and 8.30x10+1 ppm | Medium water; purity not specified | HSDB |
Formic acid critical temperature and pressure
| Property | Value | Conditions | Source |
|---|---|---|---|
| Critical temperature and pressure | 314.85 °C (598.7 °F) | HSDB |
Formic acid corrosivity
| Property | Value | Conditions | Source |
|---|---|---|---|
| Corrosivity | Corrosive to metals | HSDB |
Values compiled from PubChem Laboratory Chemical Safety Summary. Temperatures converted to Fahrenheit for reference.
09 · Fire and explosion
Formic acid fire and explosion behaviour
These are descriptions rather than measured values, so they are kept out of the table above and quoted here with the source that reported them.
Formic acid fire potential
Combustible liquid when wxposed to heat or flame ... .
Source: Hazardous Substances Data Bank (HSDB)
10 · Handling and storage
Formic acid storage and handling
Formic acid reactive group
CAMEO Chemicals places Formic acid in the reactive group Acids, Carboxylic. 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.
Formic acid safe storage
Fireproof. Store only in original container. Well closed. Separated from strong oxidants, strong bases, strong acids and food and feedstuffs. See Chemical Dangers. Keep in a well-ventilated room. Store in an area without drain or sewer access.
Source: ILO-WHO International Chemical Safety Cards (ICSCs)
Formic acid storage conditions
Store in a dry, well-ventilated place. Separate from oxidizing materials and alkaline substances.
Source: Hazardous Substances Data Bank (HSDB)
Formic acid incompatible materials
/Aluminium/ ... reduces the acid (itself a reducant) with incandescence.
Source: Hazardous Substances Data Bank (HSDB)
Formic acid reactivity
FORMIC ACID reacts exothmerically with all bases, both organic (for example, the amines) and inorganic. Reacts with active metals to form gaseous hydrogen and a metal salt. Reacts with cyanide salts to generate gaseous hydrogen cyanide. Reacts with diazo compounds, dithiocarbamates, isocyanates, mercaptans, nitrides, and sulfides to generate flammable or toxic gases. Reacts with sulfites, nitrites, thiosulfates (to give H2S and SO3), dithionites (SO2), to generate flammable and/or toxic gases and heat. Reacts with carbonates and bicarbonates to generate carbon dioxide but still heat. Can be oxidized by strong oxidizing agents and reduced by strong reducing agents. These reactions generate heat. May initiate polymerization reactions or catalyze other chemical reactions. A mixture with furfuryl alcohol exploded [Chem. Eng. News 18:72(1940)].
Source: CAMEO Chemicals
Planning storage for a mix of chemicals? Check Formic acid in the storage compatibility matrix →
11 · Transport
Formic 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.
Formic acid under UN 1779 — shipping name, class and packing group
Europe · ADR 2025, Table A
| Proper shipping name (3.1.2) | Class | Classification code | PG | Labels (column 5) |
|---|---|---|---|---|
| FORMIC ACID with more than 85 % acid by mass | 8 | CF1 | II | |
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) |
|---|---|---|---|
| Formic acid with more than 85% acid by mass | 8 | II | |
Source: 49 CFR 172.101 Hazardous Materials Table · eCFR, revision 2026-08-03. Class 8 is “Corrosive material” (49 CFR 173.2).
Formic acid under UN 3412 — shipping name, class and packing group
Europe · ADR 2025, Table A
| Proper shipping name (3.1.2) | Class | Classification code | PG | Labels (column 5) |
|---|---|---|---|---|
| FORMIC ACID with not less than 10 % but not more than 85 % acid by mass | 8 | C3 | II | |
| FORMIC ACID with not less than 5 % but less than 10 % acid by mass | 8 | C3 | 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) |
|---|---|---|---|
| Formic acid with not less than 10% but not more than 85% acid by mass | 8 | II | |
| Formic acid with not less than 5% but less than 10% acid by mass | 8 | III | |
Source: 49 CFR 172.101 Hazardous Materials Table · eCFR, revision 2026-08-03. Class 8 is “Corrosive material” (49 CFR 173.2).
12 · Questions
Formic acid — frequently asked questions
What is the CAS number of Formic acid?
The CAS number of Formic acid is 64-18-6. Its EC number is 200-579-1.
What is the chemical formula of Formic acid?
The molecular formula of Formic acid is CH2O2 and its molecular weight is 46.025 g/mol.
What does a Formic acid label have to show?
Under CLP Annex VI the label for Formic acid carries the pictograms Flame, Corrosion and Skull and crossbones and the signal word is Danger.
Is Formic acid flammable?
Yes. CLP Annex VI assigns Formic acid H226 — flammable liquid and vapour. The flash point reported for it is 68.89 °C (156 °F) (HSDB).
Is Formic acid a carcinogen?
CLP Annex VI records no harmonised carcinogenicity classification for Formic 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 Formic acid?
The US occupational exposure limit reported for Formic acid is 5.0 [ppm] (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 Formic acid?
The boiling point reported for Formic acid is 101 °C (213.8 °F) (HSDB).
What is the melting point of Formic acid?
The melting point reported for Formic acid is 8.3 °C (46.9 °F) (HSDB).
How should Formic acid be stored?
CLP Annex VI assigns Formic acid the storage statement P403. Store in a dry, well-ventilated place. Separate from oxidizing materials and alkaline substances. (Hazardous Substances Data Bank (HSDB))
Nearby
Substances next to Formic acid
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