CAS #:

Linear Formula:


MDL Number:


EC No.:



(2N) 99% Cesium Hydroxide Solution
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(3N) 99.9% Cesium Hydroxide Solution
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(4N) 99.99% Cesium Hydroxide Solution
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(5N) 99.999% Cesium Hydroxide Solution
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Cesium Hydroxide Solution Properties (Theoretical)

Compound Formula CsOH
Molecular Weight 149.91
Appearance Colorless to light yellow liquid
Melting Point 205-206 °C
Boiling Point N/A
Density 1.72 g/mL3
Solubility in H2O N/A
Exact Mass 149.908192
Monoisotopic Mass 149.908192

Cesium Hydroxide Solution Health & Safety Information

Signal Word Danger
Hazard Statements H302-H314
Hazard Codes C
Precautionary Statements P264-P270-P280-P301+P312+P330+P331-P303+P361+P353-P304+P340+P310-P305+P351+P338+P310-P363-P405-P501
Risk Codes 22-34
Safety Statements 26-36/37/39-45
RTECS Number N/A
Transport Information UN 2681 8/PG 2
WGK Germany 3
GHS Pictograms

View and Print SDS


Date Accessed: 09/24/2023
Date Revised:01/15/2022


Product Name: Cesium Hydroxide Solution

Product Number: All applicable American Elements product codes, e.g. CS-OH-02-SOL , CS-OH-03-SOL , CS-OH-04-SOL , CS-OH-05-SOL

CAS #: 21351-79-1

Relevant identified uses of the substance: Scientific research and development

Supplier details:
American Elements
10884 Weyburn Ave.
Los Angeles, CA 90024
Tel: +1 310-208-0551
Fax: +1 310-208-0351

Emergency telephone number:
Domestic, North America: +1 800-424-9300
International: +1 703-527-3887


Classification of the substance or mixture:
GHS Classification in accordance with 29 CFR 1910 (OSHA HCS)
Acute toxicity, Oral (Category 4), H302
Skin corrosion (Category 1B), H314
Serious eye damage (Category 1), H318

Corrosion - GHS05 Exclamation Mark - GHS07

Signal word: Danger

Hazard statement(s):
H302 Harmful if swallowed.
H314 Causes severe skin burns and eye damage.
H318 Causes serious eye damage.

Precautionary statement(s):
P264 Wash skin thoroughly after handling.
P270 Do not eat, drink or smoke when using this product.
P280 Wear protective gloves/ protective clothing/ eye protection/ face protection.
P301 + P312 + P330 IF SWALLOWED: Call a POISON CENTER/doctor if you feel unwell. Rinse mouth.
P301 + P330 + P331 IF SWALLOWED: Rinse mouth. Do NOT induce vomiting.
P303 + P361 + P353 IF ON SKIN (or hair): Remove/ Take off immediately all contaminated clothing. Rinse skin with water/ shower.
P304 + P340 + P310 IF INHALED: Remove victim to fresh air and keep at rest in a position
comfortable for breathing. Immediately call a POISON CENTER or doctor/ physician.
P305 + P351 + P338 + P310 IF IN EYES: Rinse cautiously with water for several minutes. Remove
contact lenses, if present and easy to do. Continue rinsing. Immediately call a POISON CENTER/doctor.
P363 Wash contaminated clothing before reuse.
P405 Store locked up.
P501 Dispose of contents/ container to an approved waste disposal plant.

Hazards not otherwise classified (HNOC) or not covered by GHS - none


Formula: HCsO
Molecular weight: 149.91 g/mol
EC-No. 244-344-1
Acute Tox. 4
Skin Corr. 1B
Eye Dam. 1
H302, H314


General advice:
Consult a physician. Show this safety data sheet to the doctor in attendance.Move out of dangerous area.

If inhaled:
If breathed in, move person into fresh air. If not breathing, give artificial respiration. Consult a physician.

In case of skin contact:
Take off contaminated clothing and shoes immediately. Wash off with soap and plenty of water. Consult a physician.

In case of eye contact:
Rinse thoroughly with plenty of water for at least 15 minutes and consult a physician.Continue rinsing eyes during transport to hospital.

If swallowed:
Do NOT induce vomiting. Never give anything by mouth to an unconscious person. Rinse mouth with water. Consult a physician.

Most important symptoms and effects, both acute and delayed:
The most important known symptoms and effects are described in the labelling (see section 2.2) and/or in section 11

Indication of any immediate medical attention and special treatment needed:
No data available


Suitable extinguishing media:
Use water spray, alcohol-resistant foam, dry chemical or carbon dioxide.

Special hazards arising from the substance or mixture:
No data available

Advice for firefighters:
Wear self-contained breathing apparatus for firefighting if necessary.


Personal precautions, protective equipment and emergency procedures:
Use personal protective equipment. Avoid breathing vapours, mist or gas. Ensure adequate ventilation. Evacuate personnel to safe areas.
For personal protection see section 8.

Environmental precautions:
Do not let product enter drains.

Methods and materials for containment and cleaning up:
Soak up with inert absorbent material and dispose of as hazardous waste. Keep in suitable, closed containers for disposal


Precautions for safe handling:
Avoid contact with skin and eyes. Avoid inhalation of vapour or mist.
For precautions see section 2.2.

Conditions for safe storage, including any incompatibilities:
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.
Store under inert gas.
Storage class (TRGS 510): Non-combustible, corrosive hazardous materials

Specific end use(s):
Apart from the uses mentioned in section 1.2 no other specific uses are stipulated.


Control parameters:
CAS-No. 21351-79-1
Control parameters: 2.000000 mg/m3; 2 mg/m3; 2.000000 mg/m3; 2 mg/m3
Basis: USA. ACGIH Threshold Limit Values (TLV); USA. ACGIH Threshold Limit Values (TLV); USA. NIOSH Recommended Exposure Limits; California permissible exposure limits for chemical contaminants (Title 8, Article 107)

Exposure controls:
Appropriate engineering controls:
Handle in accordance with good industrial hygiene and safety practice. Wash hands before breaks and at the end of workday.

Personal protective equipment:
Eye/face protection:
Tightly fitting safety goggles. Faceshield (8-inch minimum). Use equipment for eye protection tested and approved under appropriate government standards such as NIOSH (US) or EN 166(EU).
Skin protection:
Handle with gloves. Gloves must be inspected prior to use. Use proper glove removal technique (without touching glove's outer surface) to avoid skin contact with this product. Dispose of contaminated gloves after use in accordance with applicable laws and good laboratory practices. Wash and dry hands.
Body Protection:
Complete suit protecting against chemicals, The type of protective equipment must be selected according to the concentration and amount of the dangerous substance at the specific workplace.
Respiratory protection:
Where risk assessment shows air-purifying respirators are appropriate use a full-face respirator with multipurpose combination (US) or type ABEK (EN 14387) respirator cartridges as a backup to engineering controls. If the respirator is the sole means of protection, use a full-face supplied air respirator. Use respirators and components tested and approved under appropriate government standards such as NIOSH (US) or CEN (EU).
Control of environmental exposure:
Do not let product enter drains.


Appearance liquid
Odour No data available
Odour Threshold No data available
pH No data available
Melting point/freezing point No data available
Initial boiling point and boiling range No data available
Flash point No data available
Evaporation rate No data available
Flammability (solid, gas) No data available
Upper/lower flammability or explosive limits No data available
Vapour pressure No data available
Vapour density No data available
Relative density 1.72 g/mL at 25 °C (77 °F)
Water solubility No data available
Partition coefficient: noctanol/water No data available
Auto-ignition temperature No data available
Decomposition temperature No data available
Viscosity No data available
Explosive properties No data available
Oxidizing properties No data available


No data available

Chemical stability:
Stable under recommended storage conditions.

Possibility of hazardous reactions:
No data available

Conditions to avoid:
No data available

Incompatible materials:
No data available

Hazardous decomposition products:
Hazardous decomposition products formed under fire conditions. - Cesium/cesium oxides
Other decomposition products - No data available


Acute toxicity: No data available
Inhalation: No data available
Dermal: No data available

Skin corrosion/irritation: No data available

Serious eye damage/eye irritation: No data available

Respiratory or skin sensitisation: No data available

Germ cell mutagenicity: No data available

IARC: No component of this product present at levels greater than or equal to 0.1% is identified as
probable, possible or confirmed human carcinogen by IARC.
No component of this product present at levels greater than or equal to 0.1% is identified as
probable, possible or confirmed human carcinogen by IARC.
ACGIH: No component of this product present at levels greater than or equal to 0.1% is identified as a carcinogen or potential carcinogen by ACGIH.
NTP: No component of this product present at levels greater than or equal to 0.1% is identified as a
known or anticipated carcinogen by NTP.
No component of this product present at levels greater than or equal to 0.1% is identified as a
known or anticipated carcinogen by NTP.
OSHA: No component of this product present at levels greater than or equal to 0.1% is identified as a carcinogen or potential carcinogen by OSHA.
No component of this product present at levels greater than or equal to 0.1% is identified as a
carcinogen or potential carcinogen by OSHA.

Reproductive toxicity: No data available

Specific target organ toxicity - single exposure: No data available

Specific target organ toxicity - repeated exposure: No data available

Aspiration hazard: No data available

Additional Information: RTECS: Not available


Toxicity: No data available

Persistence and degradability: No data available

Bioaccumulative potential: No data available

Mobility in soil: No data available

Results of PBT and vPvB assessment:
PBT/vPvB assessment not available as chemical safety assessment not required/not conducted

Other adverse effects: No data available


Waste treatment methods:
Offer surplus and non-recyclable solutions to a licensed disposal company.

Contaminated packaging:
Dispose of as unused product.


UN number: 2681 Class: 8 Packing group: II
Proper shipping name: Cesium hydroxide solution
Reportable Quantity (RQ):
Poison Inhalation Hazard: No

UN number: 2681 Class: 8 Packing group: II EMS-No: F-A, S-B

UN number: 2681 Class: 8 Packing group: II
Proper shipping name: Caesium hydroxide solution


SARA 302 Components:
No chemicals in this material are subject to the reporting requirements of SARA Title III, Section 302.

SARA 313 Components:
This material does not contain any chemical components with known CAS numbers that exceed the threshold (De Minimis) reporting levels established by SARA Title III, Section 313.

Massachusetts Right To Know Components:
Cesium hydroxide
CAS-No. 21351-79-1

Pennsylvania Right To Know Components
CAS-No. 7732-18-5
Cesium hydroxide:
CAS-No. 21351-79-1

New Jersey Right To Know Components
CAS-No. 7732-18-5
Cesium hydroxide:
CAS-No. 21351-79-1

California Prop. 65 Components:
This product does not contain any chemicals known to State of California to cause cancer, birth defects, or any other reproductive harm.


Safety Data Sheet according to Regulation (EC) No. 1907/2006 (REACH). The above information is believed to be correct but does not purport to be all inclusive and shall be used only as a guide. The information in this document is based on the present state of our knowledge and is applicable to the product with regard to appropriate safety precautions. It does not represent any guarantee of the properties of the product. American Elements shall not be held liable for any damage resulting from handling or from contact with the above product. See reverse side of invoice or packing slip for additional terms and conditions of sale. COPYRIGHT 1997-2022 AMERICAN ELEMENTS. LICENSED GRANTED TO MAKE UNLIMITED PAPER COPIES FOR INTERNAL USE ONLY.

About Cesium Hydroxide Solution

Hydroxide Formula Diagram (-OH)Cesium Hydroxide Solution is a Cesium source for use in oxygen-sensitive applications, such as metal production. Hydroxide, the OH- anion composed of an oxygen atom bonded to a hydrogen atom, is commonly present in nature and is one of the most widely studied molecules in physical chemistry. Hydroxide compounds have diverse properties and uses, from base catalysis to detection of carbon dioxide. In a watershed 2013 experiment, scientists at JILA (the Joint Institute for Laboratory Astrophysics) achieved evaporative cooling of compounds for the first time using hydroxide molecules, a discovery that may lead to new methods of controlling chemical reactions and could impact a range of disciplines, including atmospheric science and energy production technologies. Cesium Hydroxide Solution is generally immediately available in most volumes. Ultra high purity and high purity compositions improve both optical quality and usefulness as scientific standards. Nanoscale elemental powders and suspensions, as alternative high surface area forms, may be considered. American Elements produces to many standard grades when applicable, including Mil Spec (military grade); ACS, Reagent and Technical Grade; Food, Agricultural and Pharmaceutical Grade; Optical Grade, USP and EP/BP (European Pharmacopoeia/British Pharmacopoeia) and follows applicable ASTM testing standards. Typical and custom packaging is available. Additional technical, research and safety (MSDS) information is available as is a Reference Calculator for converting relevant units of measurement.

Cesium Hydroxide Solution Synonyms

Caesium hydroxide

Chemical Identifiers

Linear Formula Cs(OH)
MDL Number MFCD00010964
EC No. 244-344-1
Beilstein/Reaxys No. N/A
Pubchem CID 62750
IUPAC Name cesium hydroxide hydrate
SMILES [OH-].[Cs+]
InchI Identifier InChI=1S/Cs.H2O/h;1H2/q+1;/p-1

Packaging Specifications

Typical bulk packaging includes palletized plastic 5 gallon/25 kg. pails, fiber and steel drums to 1 ton super sacks in full container (FCL) or truck load (T/L) quantities. Research and sample quantities and hygroscopic, oxidizing or other air sensitive materials may be packaged under argon or vacuum. Shipping documentation includes a Certificate of Analysis and Safety Data Sheet (SDS). Solutions are packaged in polypropylene, plastic or glass jars up to palletized 440 gallon liquid totes, and 36,000 lb. tanker trucks.

Related Elements


See more Cesium products. Cesium (or Caesium) (atomic symbol: Ce, atomic number: 55) is a Block S, Group 1, Period 6 element with an atomic weight of 132.9054519. The number of electrons in each of Cesium's shells is 2, 8, 18, 18, 8, 1 and its electron configuration is [Xe]6s1. Cesium Bohr ModelThe cesium atom has a radius of 265 pm and a Van der Waals radius of 343 pm. Cesium is a member of the alkali group of metals. It is one of three metals that occur as a liquid at room temperature, the others being mercury and gallium. Elemental CesiumCesium's main commercial source is pollucite ore; however, it is also found in beryl, avogadrite, pezzottaite, and londonite. Cesium was discovered by Robert Bunsen and Gustav Kirchhoff in 1860 and first isolated by Carl Setterberg in 1882. In its elemental form, cesium has a silvery gold appearance. The word Cesium originates from the Latin word "caesius," meaning "sky blue," which refers to the vibrant blue lines in its spectrum.


September 24, 2023
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