Substance profile
Hydrazine
Hydrazine is a colorless oily liquid with a penetrating odor resembling ammonia.
01 · Identification
What Hydrazine is
Hydrazine is a colorless oily liquid with a penetrating odor resembling ammonia. It boils at 114 °C, melts at 1.5 °C, is miscible with water.
Under the GHS it carries the signal word Danger. It is classed as hazardous Air Pollutants (HAPs).
02 · Identifiers
Hydrazine identifiers and molecular data
Hydrazine CAS number and EC number
Hydrazine molecular formula and molecular weight
Other names for Hydrazine
- N2H4
- Diamine
- Hydrazine (Anhydrous)
- Hydrazine Anhydrous
- Hydrazine Base
- Hydrazine, (Anhydrous)
- Hydrazine, Anhydrous
- Levoxine
- Nitrogen Hydride (N2H4)
- Oxytreat 35
03 · GHS classification
Hydrazine hazard classification
Harmonised classification under CLP Annex VI. This is the legally binding classification in the EU; other jurisdictions may differ.
Hydrazine pictograms and signal word
Hydrazine hazard class and category
| Hazard class | Category | From code | Pictogram |
|---|---|---|---|
| Flammable liquids GHS chapter 2.6 | Category 3 | H226 | GHS02 |
| Acute toxicity - oral GHS chapter 3.1 | Category 3 | H301 | GHS06 |
| Acute toxicity - dermal GHS chapter 3.1 | Category 3 | H311 | GHS06 |
| 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 |
| Skin sensitisation GHS chapter 3.4 | Category 1 or 1A or 1B | H317 | GHS07 |
| Carcinogenicity GHS chapter 3.6 | Category 1A or 1B | H350 | GHS08 |
| Hazardous to the aquatic environment - acute GHS chapter 4.1 | Category 1 | H400 | GHS09 |
| Hazardous to the aquatic environment - chronic GHS chapter 4.1 | Category 1 | H410 | GHS09 |
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.
Hydrazine hazard statements (H-codes)
| Code | Hazard statement |
|---|---|
| H226 | Flammable liquid and vapour. |
| H350 | May cause cancer <state route of exposure if it is conclusively proven that no other routes of exposure cause the hazard>. |
| H331 | Toxic if inhaled. |
| H311 | Toxic in contact with skin. |
| H301 | Toxic if swallowed. |
| H314 | Causes severe skin burns and eye damage. |
| H317 | May cause an allergic skin reaction. |
| H400 | Very toxic to aquatic life. |
| H410 | Very toxic to aquatic life with long lasting effects. |
This page lists only the codes assigned to Hydrazine. 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 Hydrazine
Our own Hydrazine 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
Hydrazine precautionary statements
CLP Annex VI assigns 25 precautionary statements to Hydrazine. 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.
Disposal
What has to happen to the contents and the empty container.
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
Hydrazine 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 | хидразин |
| Spanish español | Hidrazina |
| Czech čeština | hydrazin |
| Danish dansk | hydrazin |
| German Deutsch | Hydrazin |
| Estonian eesti | hüdrasiin |
| Greek ελληνικά | υδραζίνη |
| English English | hydrazine |
| French français | hydrazine |
| Croatian hrvatski | hidrazin |
| Italian italiano | idrazina |
| Latvian latviešu | hidrazīns |
| Lithuanian lietuvių | hidrazinas |
| Hungarian magyar | hidrazin |
| Maltese Malti | idrażina |
| Dutch Nederlands | hydrazine |
| Polish polski | hydrazyna |
| Portuguese português | hidrazina |
| Romanian română | hidrazină |
| Slovak slovenčina | hydrazín |
| Slovenian slovenščina | hidrazin |
| Finnish suomi | hydratsiini |
| Swedish svenska | hydrazin |
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
Hydrazine GHS label elements
Everything CLP Annex VI fixes for Hydrazine, laid out the way it appears on a label. The greyed lines are the parts only the supplier can fill in.
Danger
Hydrazine
- Flammable liquid and vapour.
- May cause cancer <state route of exposure if it is conclusively proven that no other routes of exposure cause the hazard>.
- Toxic if inhaled.
- Toxic in contact with skin.
- Toxic if swallowed.
- Causes severe skin burns and eye damage.
- May cause an allergic skin reaction.
- Very toxic to aquatic life.
- Very toxic to aquatic life with long lasting effects.
- Obtain special instructions before use.
- 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.
- Avoid breathing 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.
- Contaminated work clothing should not be allowed out of the workplace.
- Avoid release to the environment.
- Wear protective gloves/protective clothing/eye protection/face protection/hearing protection/…
- IF SWALLOWED:
- IF ON SKIN:
- IF INHALED:
- IF exposed or concerned:
- Immediately call a POISON CENTER/doctor/…
- Get medical advice/attention.
- Rinse mouth.
- Do NOT induce vomiting.
- If skin irritation or rash occurs:
- Wash with plenty of water/…
- Collect spillage.
- Store in a well-ventilated place.
- Dispose of contents/container to …
Supplier name, address and telephone number· Product identifier·Nominal quantity
Need this as an actual label? Open Hydrazine in the GHS label constructor →
07 · Health hazards
Hydrazine health hazards and exposure limits
Hydrazine hazard summary
Hydrazines are clear, colorless liquids with an ammonia-like odor. There are many kinds of hydrazine compounds, including hydrazine, 1,1-dimethylhydrazine, and 1,2-dimethylhydrazine. Small amounts of hydrazine occur naturally in plants. Most hydrazines are manufactured for use as rocket propellants and fuels, boiler water treatments, chemical reactants, medicines, and in cancer research. Hydrazines are highly reactive and easily catch fire.
Source: Agency for Toxic Substances and Disease Registry (ATSDR)
Hydrazine carcinogenicity classification
Evaluation: There is limited evidence in humans for the carcinogenicity of hydrazine. A positive association has been observed between exposure to hydrazine and cancer of the lung. There is sufficient evidence in experimental animals for the carcinogenicity of hydrazine. Hydrazine is probably carcinogenic to humans (Group 2A).
Source: Hazardous Substances Data Bank (HSDB)
CLASSIFICATION: B2; probable human carcinogen. BASIS FOR CLASSIFICATION: Tumors have been induced in mice, rats and hamsters following oral, inhalation or intraperitoneal administration of hydrazine and hydrazine sulfate. Hydrazine is mutagenic in numerous assays. HUMAN CARCINOGENICITY DATA: Inadequate. ANIMAL CARCINOGENICITY DATA: Sufficient.
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.
Hydrazine occupational exposure limits
| Limit | Value | Source |
|---|---|---|
| PEL | 1.0 [ppm] | Haz-Map, Information on Hazardous Chemicals and Occupational Diseases |
| PEL | 1 ppm (1.3 mg/m³) | Occupational Safety and Health Administration (OSHA) |
| PEL | TWA 1 ppm (1.3 mg/m3) [skin] See Appendix G | The National Institute for Occupational Safety and Health (NIOSH) |
| REL | 0.03 ppm (0.04 mg/m³) [120 minutes] | Occupational Safety and Health Administration (OSHA) |
| REL | Ca C 0.03 ppm (0.04 mg/m3) [2-hour] See Appendix A | The National Institute for Occupational Safety and Health (NIOSH) |
| IDLH | 50 ppm ; A potential occupational carcinogen. (NIOSH, 2024) | CAMEO Chemicals |
| IDLH | 50 ppm ; A potential occupational carcinogen. [From NPG: Hydrazine] (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
Hydrazine 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.
Hydrazine boiling point
| Property | Value | Conditions | Source |
|---|---|---|---|
| Boiling point | 113.55 °C (236.4 °F) | HSDB | |
| 120.3 °C (248.5 °F) | at 760 mmHg | HSDB | |
| 113.33 °C (236 °F) | NIOSH |
Hydrazine melting point
| Property | Value | Conditions | Source |
|---|---|---|---|
| Melting point | 1.54 °C (34.8 °F) | HSDB | |
| 127 °C (260.6 °F) | HSDB | ||
| 2.22 °C (36 °F) | NIOSH |
Hydrazine density
| Property | Value | Conditions | Source |
|---|---|---|---|
| Density | 1.0036 g/cm³ | HSDB | |
| 1.42 g/cm³ | Hydrazine dihydrochloride | HSDB | |
| 1.01 g/cm³ | NIOSH |
Hydrazine solubility
| Property | Value | Conditions | Source |
|---|---|---|---|
| Solubility | Miscible with water /1.0X10+6 mg/L/ | HSDB | |
| Very soluble in water | HSDB | ||
| Miscible with methyl, ethyl, propyl, isobutyl alcohols | HSDB |
Hydrazine vapor pressure
| Property | Value | Conditions | Source |
|---|---|---|---|
| Vapor pressure | 10 mmHg | NIOSH | |
| 14.4 mmHg | at 25 °C | HSDB |
Hydrazine flash point
| Property | Value | Conditions | Source |
|---|---|---|---|
| Flash point | 52 °C (125.6 °F) | HSDB | |
| 37.78 °C (100 °F) | HSDB | ||
| 37.22 °C (99 °F) | NIOSH |
Hydrazine autoignition temperature
| Property | Value | Conditions | Source |
|---|---|---|---|
| Autoignition temperature | 37.78 °C (100 °F) | HSDB | |
| 270 °C (518 °F) | CAMEO |
Hydrazine lower explosive limit (LEL)
| Property | Value | Conditions | Source |
|---|---|---|---|
| Lower explosive limit (LEL) | 2.9 % by volume | HSDB | |
| 4.7 % by volume | CAMEO |
Hydrazine upper explosive limit (UEL)
| Property | Value | Conditions | Source |
|---|---|---|---|
| Upper explosive limit (UEL) | 98 % by volume | HSDB | |
| 100 % by volume | CAMEO |
Hydrazine vapor density
| Property | Value | Conditions | Source |
|---|---|---|---|
| Vapor density | 1.1 (air = 1) | ICSC |
Hydrazine odor threshold
| Property | Value | Conditions | Source |
|---|---|---|---|
| Odor threshold | Odor perception threshold for hydrazine is 160 mg/L. | HSDB | |
| Odor Threshold Low: 3.0 [ppm] | Haz-Map | ||
| Odor Threshold High: 4.0 [ppm] | Haz-Map |
Hydrazine critical temperature and pressure
| Property | Value | Conditions | Source |
|---|---|---|---|
| Critical temperature and pressure | 380 °C (716 °F) | HSDB |
Values compiled from PubChem Laboratory Chemical Safety Summary. Temperatures converted to Fahrenheit for reference.
09 · Fire and explosion
Hydrazine 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.
Hydrazine fire potential
Flammable liquid. A very dangerous fire hazard when exposed to heat, flame, or oxidizing agents.
Source: Hazardous Substances Data Bank (HSDB)
10 · Handling and storage
Hydrazine storage and handling
Hydrazine reactive group
CAMEO Chemicals places Hydrazine in the reactive groups Azo, Diazo, Azido, Hydrazine, and Azide Compounds, Bases, Strong. 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.
Hydrazine safe storage
Fireproof. Separated from acids, metals, oxidants and food and feedstuffs. Keep under inert gas. Provision to contain effluent from fire extinguishing. Store in an area without drain or sewer access.
Source: ILO-WHO International Chemical Safety Cards (ICSCs)
Hydrazine storage conditions
Keep container tightly closed in a dry and well-ventilated place. Containers which are opened must be carefully resealed and kept upright to prevent leakage.
Source: Hazardous Substances Data Bank (HSDB)
Hydrazine incompatible materials
Incompatible materials: Oxidizing agents, oxygen, copper, zinc, organic materials.
Source: Hazardous Substances Data Bank (HSDB)
Hydrazine reactivity
HYDRAZINE is a powerful reducing agent. May ignite spontaneously if mixed with hydrogen peroxide or with nitric acid. Decomposes with flame on contact with many metallic oxide surfaces [Haz. Chem. Data(1966)]. While boiling a piece of polyester fiber in hydrazine in a glass beaker, a technician put a somewhat rusty pair of metal tweezers into the hydrazine, which then ignited [MCA Case History 1893 (1973)]. Forms explosive metal hydrazides when mixed with alkali metals in presence of ammonia [Mellor 8, Supp. 2:95(1967)]. During the measurement of the shock sensitivity of a mixture containing hydrazine, a drop of the mixture fell on a tetryl explosive. The tetryl immediately burst into flames [ASESB 105]. Ignites spontaneously if mixed with nitrous oxide [Mellor 8, Supp. 2:214(1967)]. Reacts explosively with potassium and sodium dichromate [Mellor 11:234(1946-1947)].
Source: CAMEO Chemicals
Planning storage for a mix of chemicals? Check Hydrazine in the storage compatibility matrix →
11 · Transport
Hydrazine 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.
Hydrazine under UN 2029 — shipping name, class and packing group
Europe · ADR 2025, Table A
| Proper shipping name (3.1.2) | Class | Classification code | PG | Labels (column 5) |
|---|---|---|---|---|
| HYDRAZINE, ANHYDROUS | 8 | CFT | 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) |
|---|---|---|---|
| Hydrazine, 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).
Hydrazine under UN 3293 — shipping name, class and packing group
Europe · ADR 2025, Table A
| Proper shipping name (3.1.2) | Class | Classification code | PG | Labels (column 5) |
|---|---|---|---|---|
| HYDRAZINE, AQUEOUS SOLUTION with not more than 37 % hydrazine, by mass | 6.1 | T4 | III | |
Source: ADR 2025, Table A of Chapter 3.2 · ECE/TRANS/352 Vol. I (UNECE). Class 6.1 is “Toxic 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) |
|---|---|---|---|
| Hydrazine, aqueous solution, with not more than 37 percent hydrazine, by mass | 6.1 | III | |
Source: 49 CFR 172.101 Hazardous Materials Table · eCFR, revision 2026-08-03. Class 6.1 is “Poisonous materials” (49 CFR 173.2).
12 · Questions
Hydrazine — frequently asked questions
What is the CAS number of Hydrazine?
The CAS number of Hydrazine is 302-01-2. Its EC number is 206-114-9.
What does a Hydrazine label have to show?
Under CLP Annex VI the label for Hydrazine carries the pictograms Flame, Skull and crossbones, Health hazard, Corrosion and Environment and the signal word is Danger.
Is Hydrazine flammable?
Yes. CLP Annex VI assigns Hydrazine H226 — flammable liquid and vapour. The flash point reported for it is 52 °C (125.6 °F) (HSDB).
Is Hydrazine a carcinogen?
Yes. CLP Annex VI classifies Hydrazine as a category 1A or 1B carcinogen and assigns it H350: may cause cancer. IARC places it in Group 2A: probably carcinogenic to humans.
What is the exposure limit for Hydrazine?
The US occupational exposure limit reported for Hydrazine is 1.0 [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 Hydrazine?
The boiling point reported for Hydrazine is 113.55 °C (236.4 °F) (HSDB).
What is the melting point of Hydrazine?
The melting point reported for Hydrazine is 1.54 °C (34.8 °F) (HSDB).
How should Hydrazine be stored?
CLP Annex VI assigns Hydrazine the storage statement P403. Keep container tightly closed in a dry and well-ventilated place. Containers which are opened must be carefully resealed and kept upright to prevent leakage. (Hazardous Substances Data Bank (HSDB))
Nearby
Substances next to Hydrazine
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