Substance profile
Methyl isothiocyanate
Methyl isothiocyanate is colorless crystals with a horseradish-like odor.
01 · Identification
What Methyl isothiocyanate is
Methyl isothiocyanate is colorless crystals with a horseradish-like odor. Its molecular formula is C2H3NS and its molecular weight is 73.12 g/mol. It boils at 119 °C, melts at 36 °C, is very soluble in water.
Under the GHS it carries the signal word Danger. It is classed as flammable agents - 3rd degree.
02 · Identifiers
Methyl isothiocyanate identifiers and molecular data
Methyl isothiocyanate CAS number and EC number
Methyl isothiocyanate molecular formula and molecular weight
03 · GHS classification
Methyl isothiocyanate hazard classification
Harmonised classification under CLP Annex VI. This is the legally binding classification in the EU; other jurisdictions may differ.
Methyl isothiocyanate pictograms and signal word
Methyl isothiocyanate hazard class and category
| Hazard class | Category | From code | Pictogram |
|---|---|---|---|
| Acute toxicity - oral GHS chapter 3.1 | Category 3 | H301 | 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 |
| 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.
Methyl isothiocyanate hazard statements (H-codes)
| Code | Hazard statement |
|---|---|
| H331 | Toxic if inhaled. |
| 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 Methyl isothiocyanate. 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 Methyl isothiocyanate
A Safety Data Sheet is written for a product, not for a substance: the supplier of the grade you actually buy issues it, so two suppliers of Methyl isothiocyanate issue two different sheets. That is why there is no single authoritative SDS for a substance to download — what there is, is the job of collecting the sheets for the products you hold and keeping them current as suppliers revise them.
04 · Precautionary statements
Methyl isothiocyanate precautionary statements
CLP Annex VI assigns 16 precautionary statements to Methyl isothiocyanate. 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
Methyl isothiocyanate 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 | метилов изотиоцианат |
| Spanish español | Isotiocianato de metilo |
| Czech čeština | methyl-isothiokyanát |
| Danish dansk | methylisothiocyanat |
| German Deutsch | Methylisothiocyanat |
| Estonian eesti | metüülisotiotsüanaat |
| Greek ελληνικά | ισοθειοκυανικό μεθύλιο ισοθειοκυανικός μεθυλεστέρας |
| English English | methyl isothiocyanate |
| French français | isothiocyanate de méthyle |
| Croatian hrvatski | metil izotiocijanat |
| Italian italiano | isotiocianato di metile |
| Latvian latviešu | metilizotiocianāts |
| Lithuanian lietuvių | metilizotiocianatas |
| Hungarian magyar | metil-izotiocianát |
| Maltese Malti | isotijoċjanat tal-metil |
| Dutch Nederlands | methylisothiocyanaat |
| Polish polski | izotiocyjanian metylu |
| Portuguese português | isotiocianato de metilo |
| Romanian română | izotiocianat de metil |
| Slovak slovenčina | metylizotiokyanát |
| Slovenian slovenščina | metil izotiocianat |
| Finnish suomi | metyyli-isotiosyanaatti |
| Swedish svenska | metylisotiocyanat |
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
Methyl isothiocyanate GHS label elements
Everything CLP Annex VI fixes for Methyl isothiocyanate, laid out the way it appears on a label. The greyed lines are the parts only the supplier can fill in.
Danger
Methyl isothiocyanate
- Toxic if inhaled.
- 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.
- 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 INHALED:
- Immediately call a POISON CENTER/doctor/…
- Get medical advice/attention.
- Rinse mouth.
- Do NOT induce vomiting.
- If skin irritation or rash occurs:
- Collect spillage.
- Dispose of contents/container to …
Supplier name, address and telephone number· Product identifier·Nominal quantity
Need this as an actual label? Open Methyl isothiocyanate in the GHS label constructor →
07 · Health hazards
Methyl isothiocyanate health hazards and exposure limits
Methyl isothiocyanate hazard summary
A strong irritant, vesicant, and lacrimator; Inhalation of high concentrations can cause bronchoconstriction, lung injury, seizures, and coma; [HSDB] May cause second or third degree burns after brief skin contact. [CHRIS] Reacts with water producing carbon dioxide and methylamine; [CAMEO] A strong skin sensitizer in animal studies; [Reference #2] Causes burns; Inhalation may cause corrosive injuries to upper respiratory tract and lungs; May cause skin sensitization and lachrymation; Toxic by ingestion and inhalation; [Alfa Aesar MSDS]
Source: Haz-Map, Information on Hazardous Chemicals and Occupational Diseases
08 · Physical and chemical properties
Methyl isothiocyanate 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.
Methyl isothiocyanate boiling point
| Property | Value | Conditions | Source |
|---|---|---|---|
| Boiling point | 119 °C (246.2 °F) | HSDB | |
| 118.89 °C (246 °F) | at 760 mmHg | CAMEO | |
| 119 °C (246.2 °F) | at 760 mmHg | DOE PAC |
Methyl isothiocyanate melting point
| Property | Value | Conditions | Source |
|---|---|---|---|
| Melting point | 36 °C (96.8 °F) | HSDB | |
| 35.56 °C (96 °F) | range, midpoint shown | CAMEO |
Methyl isothiocyanate density
| Property | Value | Conditions | Source |
|---|---|---|---|
| Density | 1.0691 g/cm³ | at 37 °C | HSDB |
| 1.069 g/cm³ | at 37 °C | CAMEO | |
| 0.94 g/cm³ | range, midpoint shown | JECFA |
Methyl isothiocyanate solubility
| Property | Value | Conditions | Source |
|---|---|---|---|
| Solubility | Very soluble in ethyl ether | HSDB | |
| In water, 7.6X10+3 mg/L at 25 °C | at 25 °C | HSDB |
Methyl isothiocyanate vapor pressure
| Property | Value | Conditions | Source |
|---|---|---|---|
| Vapor pressure | 39.29 mmHg | CAMEO | |
| 19 mmHg | at 20 °C | DOE PAC | |
| 3.54 mmHg | at 25 °C | HSDB |
Methyl isothiocyanate flash point
| Property | Value | Conditions | Source |
|---|---|---|---|
| Flash point | 35 °C (95 °F) | MITC-Fume | HSDB |
| -6.67 °C (20 °F) | Haz-Map |
Methyl isothiocyanate autoignition temperature
| Property | Value | Conditions | Source |
|---|---|---|---|
| Autoignition temperature | 370 °C (698 °F) | HSDB |
Methyl isothiocyanate lower explosive limit (LEL)
| Property | Value | Conditions | Source |
|---|---|---|---|
| Lower explosive limit (LEL) | 2.5 % by volume | HSDB | |
| Product vapor forms explosive mixtures with air; prevent build-up of electrostatic charges, sparks, and open flame. | MITC-Fume | HSDB |
Methyl isothiocyanate upper explosive limit (UEL)
| Property | Value | Conditions | Source |
|---|---|---|---|
| Upper explosive limit (UEL) | 30 % by volume | MITC-Fume | HSDB |
Methyl isothiocyanate vapor density
| Property | Value | Conditions | Source |
|---|---|---|---|
| Vapor density | 2.53 (air = 1) | HSDB |
Methyl isothiocyanate odor threshold
| Property | Value | Conditions | Source |
|---|---|---|---|
| Odor threshold | Odor Threshold Low: 1.7 [ppm] | Haz-Map |
Methyl isothiocyanate corrosivity
| Property | Value | Conditions | Source |
|---|---|---|---|
| Corrosivity | Corrosive to iron, zinc and other metals | HSDB |
Values compiled from PubChem Laboratory Chemical Safety Summary. Temperatures converted to Fahrenheit for reference.
09 · Fire and explosion
Methyl isothiocyanate 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.
Methyl isothiocyanate fire potential
Flammable
Source: Hazardous Substances Data Bank (HSDB)
Solubility
Readily soluble in common organic solvents, such as ethanol, methanol, acetone, cyclohexanone, dichloromethane, chloroform, carbon tetrachloride, benzene, xylene, petroleum ether, and mineral oils.
Source: HSDB
Odor
In the olfactory threshold study, 33 individuals (16 males, 17 females) with a mean age of 25 years (range, 18 to 34 years) were tested. They were exposed to three positive control odorants, pyridine, acetic acid, and n-butyl alcohol, as well as to MITC. The technician chose the odorant and concentration level. The odorant was dispensed in double blind fashion from one of three presentation ports. The subject was responsible for identifying from which of the presentation ports the odorant was dispersed. A 30-second rest period between exposures was permitted in order to allow the subject to recover prior to the next exposure. The operator tested each subject over the range of concentrations for each odorant until he was assured that the threshold had been adequately ascertained. A standard procedure was employed in order to make this determination. The observed odor threshold for MITC ranged from 0.2 to 8 ppm with a geometric mean of 1.7 ppm. ...
Source: HSDB
10 · Handling and storage
Methyl isothiocyanate storage and handling
Methyl isothiocyanate storage conditions
Store only in closed original container to prevent leakage. Store only in cool, well-ventilated, locked areas, away form food and feedstuff, out of reach of children and irresponsible persons. Avoid exposure to heat and/or direct sunlight. Do not drop container onto or slide across sharp objects. /MLPC Methylisothiocyanate (MITC)/
Source: Hazardous Substances Data Bank (HSDB)
Methyl isothiocyanate incompatible materials
... Can react vigorously with oxidizing materials.
Source: Hazardous Substances Data Bank (HSDB)
Methyl isothiocyanate reactivity
Isocyanates and thioisocyanates, such as METHYL ISOTHIOCYANATE, are incompatible with many classes of compounds, reacting exothermically to release toxic gases. Reactions with amines, aldehydes, alcohols, alkali metals, ketones, mercaptans, strong oxidizers, hydrides, phenols, and peroxides can cause vigorous releases of heat. Acids and bases initiate polymerization reactions in these materials. Some isocyanates react with water to form amines and liberate carbon dioxide. Polyurethanes are formed by the condensation reaction of diisocyanates with, for example, ethyl glycol.
Source: CAMEO Chemicals
Planning storage for a mix of chemicals? Check Methyl isothiocyanate in the storage compatibility matrix →
11 · Transport
Methyl isothiocyanate 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.
Methyl isothiocyanate under UN 2477 — shipping name, class and packing group
Europe · ADR 2025, Table A
| Proper shipping name (3.1.2) | Class | Classification code | PG | Labels (column 5) |
|---|---|---|---|---|
| METHYL ISOTHIOCYANATE | 6.1 | TF1 | I | |
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) |
|---|---|---|---|
| Methyl isothiocyanate | 6.1 | I | |
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
Methyl isothiocyanate — frequently asked questions
What is the CAS number of Methyl isothiocyanate?
The CAS number of Methyl isothiocyanate is 556-61-6. Its EC number is 209-132-5.
What is the chemical formula of Methyl isothiocyanate?
The molecular formula of Methyl isothiocyanate is C2H3NS and its molecular weight is 73.12 g/mol.
What does a Methyl isothiocyanate label have to show?
Under CLP Annex VI the label for Methyl isothiocyanate carries the pictograms Skull and crossbones, Corrosion and Environment and the signal word is Danger.
Is Methyl isothiocyanate flammable?
CLP Annex VI assigns Methyl isothiocyanate 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 35 °C (95 °F), MITC-Fume (HSDB).
Is Methyl isothiocyanate a carcinogen?
CLP Annex VI records no harmonised carcinogenicity classification for Methyl isothiocyanate. 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 boiling point of Methyl isothiocyanate?
The boiling point reported for Methyl isothiocyanate is 119 °C (246.2 °F) (HSDB).
What is the melting point of Methyl isothiocyanate?
The melting point reported for Methyl isothiocyanate is 36 °C (96.8 °F) (HSDB).
How should Methyl isothiocyanate be stored?
Store only in closed original container to prevent leakage. Store only in cool, well-ventilated, locked areas, away form food and feedstuff, out of reach of children and irresponsible persons. Avoid exposure to heat and/or direct sunlight. Do not drop container onto or slide across sharp objects. /MLPC Methylisothiocyanate (MITC)/ (Hazardous Substances Data Bank (HSDB))
Nearby
Substances next to Methyl isothiocyanate
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