Substance profile
Calcium hypochlorite
Calcium hypochlorite is a powder with a strong chlorine odor.
01 · Identification
What Calcium hypochlorite is
Calcium hypochlorite is a powder with a strong chlorine odor. Its molecular formula is CaCl2O2 and its molecular weight is 142.98 g/mol. It boils at 100 °C, melts at 100 °C.
Under the GHS it carries the signal word Danger. It is classed as reactive agents - 1st degree.
02 · Identifiers
Calcium hypochlorite identifiers and molecular data
Calcium hypochlorite CAS number and EC number
Calcium hypochlorite molecular formula and molecular weight
Other names for Calcium hypochlorite
- pool chlorine
- cal hypo
- Ca(ClO)2
03 · GHS classification
Calcium hypochlorite hazard classification
Harmonised classification under CLP Annex VI. This is the legally binding classification in the EU; other jurisdictions may differ.
Calcium hypochlorite pictograms and signal word
Calcium hypochlorite hazard class and category
| Hazard class | Category | From code | Pictogram |
|---|---|---|---|
| Oxidising liquids or Oxidising solids | Category 2 or 3 | H272 | GHS03 |
| Acute toxicity - oral GHS chapter 3.1 | Category 4 | H302 | GHS07 |
| Skin corrosion/irritation GHS chapter 3.2 | Category 1A or 1B or 1C | H314 | GHS05 |
| Hazardous to the aquatic environment - acute GHS chapter 4.1 | Category 1 | H400 | 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.
Calcium hypochlorite hazard statements (H-codes)
| Code | Hazard statement |
|---|---|
| H272 | May intensify fire; oxidiser. |
| H302 | Harmful if swallowed. |
| H314 | Causes severe skin burns and eye damage. |
| H400 | Very toxic to aquatic life. |
Calcium hypochlorite supplemental EU statements (EUH)
| Code | Statement |
|---|---|
| EUH031 | Contact with acids liberates toxic gas. |
This page lists only the codes assigned to Calcium hypochlorite. 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 Calcium hypochlorite
Our own Calcium hypochlorite 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
Calcium hypochlorite precautionary statements
CLP Annex VI assigns 11 precautionary statements to Calcium hypochlorite. 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
Calcium hypochlorite 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 | калциев хипохлорит |
| Spanish español | Hipoclorito de calcio |
| Czech čeština | chlornan vápenatý |
| Danish dansk | calciumhypochlorit |
| German Deutsch | Calciumhypochlorit |
| Estonian eesti | kaltsiumhüpoklorit |
| Greek ελληνικά | υποχλωριώδες ασβέστιο |
| English English | calcium hypochlorite |
| French français | hypochlorite de calcium |
| Croatian hrvatski | kalcijev hipoklorit |
| Italian italiano | ipoclorito di calcio |
| Latvian latviešu | kalcija hipohlorīts |
| Lithuanian lietuvių | kalcio hipochloritas |
| Hungarian magyar | kálcium-hipoklorit |
| Maltese Malti | ipoklorit tal-kalċju |
| Dutch Nederlands | calciumhypochloriet |
| Polish polski | podchloryn wapnia chloran(I) wapnia |
| Portuguese português | hipoclorito de cálcio |
| Romanian română | hipoclorit de calciu |
| Slovak slovenčina | chlórnan vápenatý |
| Slovenian slovenščina | kalcijev hipoklorit |
| Finnish suomi | kalsiumhypokloriitti |
| Swedish svenska | kalciumhypoklorit |
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
Calcium hypochlorite GHS label elements
Everything CLP Annex VI fixes for Calcium hypochlorite, laid out the way it appears on a label. The greyed lines are the parts only the supplier can fill in.
Danger
Calcium hypochlorite
- May intensify fire; oxidiser.
- Harmful if swallowed.
- Causes severe skin burns and eye damage.
- Very toxic to aquatic life.
- Contact with acids liberates toxic gas.
- Do not breathe dust/fume/gas/mist/vapours/spray.
- Do not eat, drink or smoke when using this product.
- Avoid release to the environment.
- Wear protective gloves/protective clothing/eye protection/face protection/hearing protection/…
- IF SWALLOWED:
- Immediately call a POISON CENTER/doctor/…
- Call a POISON CENTER/doctor/… if you feel unwell.
- Rinse mouth.
- Do NOT induce vomiting.
- Collect spillage.
- Dispose of contents/container to …
Supplier name, address and telephone number· Product identifier·Nominal quantity
Need this as an actual label? Open Calcium hypochlorite in the GHS label constructor →
07 · Health hazards
Calcium hypochlorite health hazards and exposure limits
Calcium hypochlorite hazard summary
An oxidizer that promotes combustion; Decomposes in the presence of heat, water, or contamination with release of corrosive chlorine gas; Calcium hypochlorite solutions are corrosive to the skin, eyes, and upper respiratory tract; [CHEMINFO] See Hypochlorous acid.
Source: Haz-Map, Information on Hazardous Chemicals and Occupational Diseases
Calcium hypochlorite carcinogenicity classification
Evaluation: There is inadequate evidence for the carcinogenicity of hypochlorite salts in experimental animals. No data were available from studies in humans on the carcinogenicity of hypochlorite salts. Overall evaluation: Hypochlorite salts are not classifiable as to their carcinogenicity to humans (Group 3). /Hypochlorite salts/
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.
08 · Physical and chemical properties
Calcium hypochlorite 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.
Calcium hypochlorite boiling point
| Property | Value | Conditions | Source |
|---|---|---|---|
| Boiling point | 100 °C (212 °F) | decomposes | HSDB |
Calcium hypochlorite melting point
| Property | Value | Conditions | Source |
|---|---|---|---|
| Melting point | 100 °C (212 °F) | HSDB |
Calcium hypochlorite density
| Property | Value | Conditions | Source |
|---|---|---|---|
| Density | 2.35 g/cm³ | HSDB | |
| 2.35 g/cm³ | at 25 °C | DOE PAC |
Calcium hypochlorite solubility
| Property | Value | Conditions | Source |
|---|---|---|---|
| Solubility | 21% in water at 25 °C | at 25 °C | HSDB |
| Solubility in water, g/100ml at 25 °C: 21 | at 25 °C | ICSC |
Calcium hypochlorite corrosivity
| Property | Value | Conditions | Source |
|---|---|---|---|
| Corrosivity | 0.001 mm ASTM grade 2 titanium/yr at 6 wt% and 100 °C | From table | HSDB |
Values compiled from PubChem Laboratory Chemical Safety Summary. Temperatures converted to Fahrenheit for reference.
09 · Fire and explosion
Calcium hypochlorite 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.
Calcium hypochlorite fire potential
Contact with combustible materials will increase fire hazard. May undergo accelerated decomposition with release of heat above 350 °F (177 °C). /Calcium hypochlorite, dry, or calcium hypochlorite, mixtures, dry/
Source: Hazardous Substances Data Bank (HSDB)
10 · Handling and storage
Calcium hypochlorite storage and handling
Calcium hypochlorite reactive group
CAMEO Chemicals places Calcium hypochlorite in the reactive groups Oxidizing Agents, Strong, Salts, Basic. 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.
Calcium hypochlorite safe storage
Well closed. Store in an area without drain or sewer access. Separated from food and feedstuffs. See Chemical Dangers.
Source: ILO-WHO International Chemical Safety Cards (ICSCs)
Calcium hypochlorite storage conditions
Store in a cool, dry, well-ventilated location at a temperature below 120 °F (50 °C) to avoid slow decomposition. Separate from oxidizing materils, acids, ammonia, amines, and other chlorinating agents. Immediately remove and properly dispose of any spilled material. /Calcium hypochlorite, dry or calcium hypochlorite, mixtures, dry/
Source: Hazardous Substances Data Bank (HSDB)
Calcium hypochlorite incompatible materials
Reacts with water and with acids releasing chlorine. Forms explosive compounds with ammonia and amines. Strong oxidizer. Other incompatible materials include organics, nitrogen containing compounds, dry chemical fire extinguishers containing mono-ammonium phosphate, combustible or flammable materials. /Calcium hypochlorite, dry or calcium hypochlorite, mixtures, dry/
Source: Hazardous Substances Data Bank (HSDB)
Calcium hypochlorite reactivity
BLEACHING POWDER is a strong oxidizing agent and a base. Acts in aqueous solution by releasing hypochlorite ion (OCl- ion). Decomposes on standing to give oxygen (a strong oxidizing agent) and calcium chloride. Mixing of bleaching powder (hypochlorite solution) with ammonia solutions produces toxic/explosive ammonia trichloride vapors.
Source: CAMEO Chemicals
Planning storage for a mix of chemicals? Check Calcium hypochlorite in the storage compatibility matrix →
11 · Transport
Calcium hypochlorite 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.
Calcium hypochlorite under UN 1748 — shipping name, class and packing group
Europe · ADR 2025, Table A
| Proper shipping name (3.1.2) | Class | Classification code | PG | Labels (column 5) |
|---|---|---|---|---|
| CALCIUM HYPOCHLORITE, DRY or CALCIUM HYPOCHLORITE MIXTURE, DRY with more than 39 % available chlorine (8.8 % available oxygen) | 5.1 | O2 | II | |
| CALCIUM HYPOCHLORITE, DRY or CALCIUM HYPOCHLORITE MIXTURE, DRY with more than 39 % available chlorine (8.8 % available oxygen) | 5.1 | O2 | III | |
Source: ADR 2025, Table A of Chapter 3.2 · ECE/TRANS/352 Vol. I (UNECE). Class 5.1 is “Oxidizing 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) |
|---|---|---|---|
| Calcium hypochlorite, dry or Calcium hypochlorite mixture dry with more than 39% available chlorine (8.8% available oxygen) | 5.1 | II | |
| Calcium hypochlorite, dry or Calcium hypochlorite mixture dry with more than 39% available chlorine (8.8% available oxygen) | 5.1 | III | |
Source: 49 CFR 172.101 Hazardous Materials Table · eCFR, revision 2026-08-03. Class 5.1 is “Oxidizer” (49 CFR 173.2).
Calcium hypochlorite under UN 2208 — shipping name, class and packing group
Europe · ADR 2025, Table A
| Proper shipping name (3.1.2) | Class | Classification code | PG | Labels (column 5) |
|---|---|---|---|---|
| CALCIUM HYPOCHLORITE MIXTURE, DRY with more than 10 % but not more than 39 % available chlorine | 5.1 | O2 | III | |
Source: ADR 2025, Table A of Chapter 3.2 · ECE/TRANS/352 Vol. I (UNECE). Class 5.1 is “Oxidizing 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) |
|---|---|---|---|
| Calcium hypochlorite mixture, dry, with more than 10% but not more than 39% available chlorine | 5.1 | III | |
Source: 49 CFR 172.101 Hazardous Materials Table · eCFR, revision 2026-08-03. Class 5.1 is “Oxidizer” (49 CFR 173.2).
Calcium hypochlorite under UN 2880 — shipping name, class and packing group
Europe · ADR 2025, Table A
| Proper shipping name (3.1.2) | Class | Classification code | PG | Labels (column 5) |
|---|---|---|---|---|
| CALCIUM HYPOCHLORITE, HYDRATED, or CALCIUM HYPOCHLORITE, HYDRATED MIXTURE, with not less than 5.5 % but not more than 16 % water | 5.1 | O2 | II | |
| CALCIUM HYPOCHLORITE, HYDRATED, or CALCIUM HYPOCHLORITE, HYDRATED MIXTURE, with not less than 5.5 % but not more than 16 % water | 5.1 | O2 | III | |
Source: ADR 2025, Table A of Chapter 3.2 · ECE/TRANS/352 Vol. I (UNECE). Class 5.1 is “Oxidizing 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) |
|---|---|---|---|
| Calcium hypochlorite, hydrated or Calcium hypochlorite, hydrated mixture, with not less than 5.5% but not more than 16% water | 5.1 | II | |
| Calcium hypochlorite, hydrated or Calcium hypochlorite, hydrated mixture, with not less than 5.5% but not more than 16% water | 5.1 | III | |
Source: 49 CFR 172.101 Hazardous Materials Table · eCFR, revision 2026-08-03. Class 5.1 is “Oxidizer” (49 CFR 173.2).
Calcium hypochlorite under UN 3485 — shipping name, class and packing group
Europe · ADR 2025, Table A
| Proper shipping name (3.1.2) | Class | Classification code | PG | Labels (column 5) |
|---|---|---|---|---|
| CALCIUM HYPOCHLORITE, DRY, CORROSIVE or CALCIUM HYPOCHLORITE MIXTURE, DRY, CORROSIVE with more than 39 % available chlorine (8.8 % available oxygen) | 5.1 | OC2 | II | |
Source: ADR 2025, Table A of Chapter 3.2 · ECE/TRANS/352 Vol. I (UNECE). Class 5.1 is “Oxidizing 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) |
|---|---|---|---|
| Calcium hypochlorite, dry, corrosive or Calcium hypochlorite mixture, dry, corrosive with more than 39% available chlorine (8.8% available oxygen) | 5.1 | II | |
Source: 49 CFR 172.101 Hazardous Materials Table · eCFR, revision 2026-08-03. Class 5.1 is “Oxidizer” (49 CFR 173.2).
Calcium hypochlorite under UN 3486 — shipping name, class and packing group
Europe · ADR 2025, Table A
| Proper shipping name (3.1.2) | Class | Classification code | PG | Labels (column 5) |
|---|---|---|---|---|
| CALCIUM HYPOCHLORITE MIXTURE, DRY, CORROSIVE with more than 10 % but not more than 39 % available chlorine | 5.1 | OC2 | III | |
Source: ADR 2025, Table A of Chapter 3.2 · ECE/TRANS/352 Vol. I (UNECE). Class 5.1 is “Oxidizing 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) |
|---|---|---|---|
| Calcium hypochlorite mixture, dry, corrosive with more than 10% but not more than 39% available chlorine | 5.1 | III | |
Source: 49 CFR 172.101 Hazardous Materials Table · eCFR, revision 2026-08-03. Class 5.1 is “Oxidizer” (49 CFR 173.2).
Calcium hypochlorite under UN 3487 — shipping name, class and packing group
Europe · ADR 2025, Table A
| Proper shipping name (3.1.2) | Class | Classification code | PG | Labels (column 5) |
|---|---|---|---|---|
| CALCIUM HYPOCHLORITE, HYDRATED, CORROSIVE or CALCIUM HYPOCHLORITE, HYDRATED MIXTURE, CORROSIVE with not less than 5.5 % but not more than 16 % water | 5.1 | OC2 | II | |
| CALCIUM HYPOCHLORITE, HYDRATED, CORROSIVE or CALCIUM HYPOCHLORITE, HYDRATED MIXTURE, CORROSIVE with not less than 5.5 % but not more than 16 % water | 5.1 | OC2 | III | |
Source: ADR 2025, Table A of Chapter 3.2 · ECE/TRANS/352 Vol. I (UNECE). Class 5.1 is “Oxidizing 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) |
|---|---|---|---|
| Calcium hypochlorite, hydrated, corrosive or Calcium hypochlorite, hydrated mixture, corrosive with not less than 5.5% but not more than 16% water | 5.1 | II | |
| Calcium hypochlorite, hydrated, corrosive or Calcium hypochlorite, hydrated mixture, corrosive with not less than 5.5% but not more than 16% water | 5.1 | III | |
Source: 49 CFR 172.101 Hazardous Materials Table · eCFR, revision 2026-08-03. Class 5.1 is “Oxidizer” (49 CFR 173.2).
12 · Questions
Calcium hypochlorite — frequently asked questions
What is the CAS number of Calcium hypochlorite?
The CAS number of Calcium hypochlorite is 7778-54-3. Its EC number is 231-908-7.
What is the chemical formula of Calcium hypochlorite?
The molecular formula of Calcium hypochlorite is CaCl2O2 and its molecular weight is 142.98 g/mol.
What does a Calcium hypochlorite label have to show?
Under CLP Annex VI the label for Calcium hypochlorite carries the pictograms Flame over circle, Corrosion, Exclamation mark and Environment and the signal word is Danger.
Is Calcium hypochlorite flammable?
CLP Annex VI assigns Calcium hypochlorite 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.
Is Calcium hypochlorite a carcinogen?
CLP Annex VI records no harmonised carcinogenicity classification for Calcium hypochlorite. 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 Calcium hypochlorite?
The boiling point reported for Calcium hypochlorite is 100 °C (212 °F), decomposes (HSDB).
What is the melting point of Calcium hypochlorite?
The melting point reported for Calcium hypochlorite is 100 °C (212 °F) (HSDB).
How should Calcium hypochlorite be stored?
Store in a cool, dry, well-ventilated location at a temperature below 120 °F (50 °C) to avoid slow decomposition. Separate from oxidizing materils, acids, ammonia, amines, and other chlorinating agents. Immediately remove and properly dispose of any spilled material. /Calcium hypochlorite, dry or calcium hypochlorite, mixtures, dry/ (Hazardous Substances Data Bank (HSDB))
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