Substance profile
Thioglycolic Acid
Thioglycolic Acid is a colorless liquid with a strong, unpleasant odor.
01 · Identification
What Thioglycolic Acid is
Thioglycolic Acid is a colorless liquid with a strong, unpleasant odor. Its molecular formula is C2H4O2S and its molecular weight is 92.12 g/mol. It boils at 120 °C, melts at -16.5 °C, is miscible with water.
Under the GHS it carries the signal word Danger. It is classed as corrosives.
02 · Identifiers
Thioglycolic Acid identifiers and molecular data
Thioglycolic Acid CAS number and EC number
Thioglycolic Acid molecular formula and molecular weight
03 · GHS classification
Thioglycolic Acid hazard classification
Harmonised classification under CLP Annex VI. This is the legally binding classification in the EU; other jurisdictions may differ.
Thioglycolic Acid pictograms and signal word
Thioglycolic Acid hazard class and category
| Hazard class | Category | From code | Pictogram |
|---|---|---|---|
| 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 |
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.
Thioglycolic Acid hazard statements (H-codes)
| Code | Hazard statement |
|---|---|
| H331 | Toxic if inhaled. |
| H311 | Toxic in contact with skin. |
| H301 | Toxic if swallowed. |
| H314 | Causes severe skin burns and eye damage. |
This page lists only the codes assigned to Thioglycolic 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 Thioglycolic Acid
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 Thioglycolic Acid 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
Thioglycolic Acid precautionary statements
CLP Annex VI assigns 11 precautionary statements to Thioglycolic 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
Thioglycolic 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 | тиогликолова киселина |
| Spanish español | Ácido tioglicólico |
| Czech čeština | thioglykolová kyselina |
| Danish dansk | thioglycolsyre |
| German Deutsch | Thioglycolsäure MercaptoessigsäureThiolessigsäure |
| Estonian eesti | tioglükoolhape |
| Greek ελληνικά | θειογλυκολικό οξύ |
| English English | thioglycolic acid |
| French français | acide thioglycolique |
| Croatian hrvatski | tioglikolna kiselina |
| Italian italiano | acido tioglicolico |
| Latvian latviešu | tioglikolskābe |
| Lithuanian lietuvių | tioglikolio rūgštis |
| Hungarian magyar | tioglikolsav, merkaptoecetsav |
| Maltese Malti | aċidu tijoglikoliku |
| Dutch Nederlands | thioglycolzuur |
| Polish polski | kwas 2-sulfanylooctowy kwas tioglikolowykwas merkaptooctowy |
| Portuguese português | ácido tioglicólico |
| Romanian română | acid tioglicolic |
| Slovak slovenčina | kyselina tioglykolová |
| Slovenian slovenščina | tioglikolna kislina |
| Finnish suomi | tioglykolihappo |
| Swedish svenska | tioglykolsyra |
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
Thioglycolic Acid GHS label elements
Everything CLP Annex VI fixes for Thioglycolic Acid, laid out the way it appears on a label. The greyed lines are the parts only the supplier can fill in.
Danger
Thioglycolic Acid
- Toxic if inhaled.
- Toxic in contact with skin.
- Toxic 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 Thioglycolic Acid in the GHS label constructor →
07 · Health hazards
Thioglycolic Acid health hazards and exposure limits
Thioglycolic Acid hazard summary
Toxicological properties are similar to those of acetic acid. May cause skin irritation in professional hairdressers; Ammonium thioglycolate causes allergic contact dermatitis. Thioglycolic acid and its salts and esters can be irritating to the skin and eyes and repeated exposure can cause skin sensitization. [ACGIH] Corrosive to skin; [Quick CPC] A corrosive substance that can cause pulmonary edema; [ICSC] Danger of skin sensitization; [MAK]
Source: Haz-Map, Information on Hazardous Chemicals and Occupational Diseases
Thioglycolic Acid occupational exposure limits
| Limit | Value | Source |
|---|---|---|
| PEL | none See Appendix G | The National Institute for Occupational Safety and Health (NIOSH) |
| REL | 1 ppm (4 mg/m³) | Occupational Safety and Health Administration (OSHA) |
| REL | TWA 1 ppm (4 mg/m3) [skin] | The National Institute for Occupational Safety and Health (NIOSH) |
| IDLH | N.D. | The National Institute for Occupational Safety and Health (NIOSH) |
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
Thioglycolic 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.
Thioglycolic Acid boiling point
| Property | Value | Conditions | Source |
|---|---|---|---|
| Boiling point | 120 °C (248 °F) | ICSC | |
| 120 °C (248 °F) | at 20 mmHg (reduced pressure) | HSDB |
Thioglycolic Acid melting point
| Property | Value | Conditions | Source |
|---|---|---|---|
| Melting point | -16.5 °C (2.3 °F) | HSDB | |
| -16.67 °C (2 °F) | NIOSH |
Thioglycolic Acid density
| Property | Value | Conditions | Source |
|---|---|---|---|
| Density | 1.32 g/cm³ | NIOSH | |
| 1.3253 g/cm³ | at 20 °C | HSDB |
Thioglycolic Acid solubility
| Property | Value | Conditions | Source |
|---|---|---|---|
| Solubility | Miscible with water | HSDB | |
| Miscible with chloroform, benzene and many other organic solvents | HSDB | ||
| Miscible with ethanol, and ethyl ether; slightly soluble in chloroform | HSDB |
Thioglycolic Acid vapor pressure
| Property | Value | Conditions | Source |
|---|---|---|---|
| Vapor pressure | 0.0868 mmHg | at 25 °C | HSDB |
| 9.7508 mmHg | at 18 °C | ICSC |
Thioglycolic Acid flash point
| Property | Value | Conditions | Source |
|---|---|---|---|
| Flash point | 130 °C (266 °F) | Closed cup | HSDB |
| 112.78 °C (235 °F) | CAMEO | ||
| 126 °C (258.8 °F) | ICSC |
Thioglycolic Acid autoignition temperature
| Property | Value | Conditions | Source |
|---|---|---|---|
| Autoignition temperature | 350 °C (662 °F) | HSDB |
Thioglycolic Acid lower explosive limit (LEL)
| Property | Value | Conditions | Source |
|---|---|---|---|
| Lower explosive limit (LEL) | 5.9 % by volume | HSDB |
Thioglycolic Acid vapor density
| Property | Value | Conditions | Source |
|---|---|---|---|
| Vapor density | 3.18 (air = 1) | HSDB | |
| 3.2 (air = 1) | ICSC |
Thioglycolic 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
Thioglycolic Acid storage and handling
Thioglycolic Acid safe storage
Separated from strong oxidants, strong bases, food and feedstuffs and combustible substances. Keep in a well-ventilated room.
Source: ILO-WHO International Chemical Safety Cards (ICSCs)
Thioglycolic Acid 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. Recommended storage temperature: -20 °C
Source: Hazardous Substances Data Bank (HSDB)
Thioglycolic Acid incompatible materials
Strong oxidizing agents, Strong acids
Source: Hazardous Substances Data Bank (HSDB)
Thioglycolic Acid reactivity
THIOGLYCOLIC ACID is readily oxidized by air (NTP, 1992). Reacts readily with other oxidizing agents as well in reactions that may generate toxic gases. Incompatible with diazo and azo compounds, halocarbons, isocyanates, aldehydes, alkali metals, nitrides, hydrides, and other strong reducing agents. Reactions with these materials may generate heat and toxic and flammable gases. May react with acids to liberate hydrogen sulfide. Neutralizes bases in exothermic reactions. Reacts with cyanides, sulfites, nitrites, thiosulfates to generate flammable and toxic gases and heat. Reacts with carbonates and bicarbonates.
Source: CAMEO Chemicals
Planning storage for a mix of chemicals? Check Thioglycolic Acid in the storage compatibility matrix →
10 · Transport
Thioglycolic 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.
Thioglycolic Acid under UN 1940 — shipping name, class and packing group
Europe · ADR 2025, Table A
| Proper shipping name (3.1.2) | Class | Classification code | PG | Labels (column 5) |
|---|---|---|---|---|
| THIOGLYCOLIC ACID | 8 | C3 | 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) |
|---|---|---|---|
| Thioglycolic acid | 8 | II | |
Source: 49 CFR 172.101 Hazardous Materials Table · eCFR, revision 2026-08-03. Class 8 is “Corrosive material” (49 CFR 173.2).
11 · Questions
Thioglycolic Acid — frequently asked questions
What is the CAS number of Thioglycolic Acid?
The CAS number of Thioglycolic Acid is 68-11-1. Its EC number is 200-677-4.
What is the chemical formula of Thioglycolic Acid?
The molecular formula of Thioglycolic Acid is C2H4O2S and its molecular weight is 92.12 g/mol.
What does a Thioglycolic Acid label have to show?
Under CLP Annex VI the label for Thioglycolic Acid carries the pictograms Skull and crossbones and Corrosion and the signal word is Danger.
Is Thioglycolic Acid flammable?
CLP Annex VI assigns Thioglycolic 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 130 °C (266 °F), Closed cup (HSDB).
Is Thioglycolic Acid a carcinogen?
CLP Annex VI records no harmonised carcinogenicity classification for Thioglycolic 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 Thioglycolic Acid?
The US occupational exposure limit reported for Thioglycolic Acid is none See Appendix G (The National Institute for Occupational Safety and Health (NIOSH)). 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 Thioglycolic Acid?
The boiling point reported for Thioglycolic Acid is 120 °C (248 °F) (ICSC).
What is the melting point of Thioglycolic Acid?
The melting point reported for Thioglycolic Acid is -16.5 °C (2.3 °F) (HSDB).
How should Thioglycolic Acid be stored?
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. Recommended storage temperature: -20 °C (Hazardous Substances Data Bank (HSDB))
Nearby
Substances next to Thioglycolic Acid
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