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Cesium hydroxide

CAS No.
21351-79-1
Chemical Name:
Cesium hydroxide
Synonyms
CsOH;Caesium hydoxide;Cesiumhydroxide,50%aqueoussolution(99.9%-Cs);Cesium hydoxide;Cesium hydroxide;Cesium hydroxide;cesiumhydroxidedimer;Cesium hydroxide dimer;Caesium Hydroxide 99.9%;cesiumhydroxide(cs(oh))
CBNumber:
CB7357929
Molecular Formula:
CsHO
Molecular Weight:
149.91
MDL Number:
MFCD00149664
MOL File:
21351-79-1.mol
MSDS File:
SDS
TDS File:
TDS
Last updated:2026-06-23 16:59:16

Cesium hydroxide Properties

Melting point 272 °C(lit.)
Density 3.68 g/mL at 25 °C(lit.)
solubility Miscible with ethanol.
form Liquid
pka 11.6[at 20 ℃]
color Colorless
Water Solubility soluble
Specific Heat Capacity Cp(crystal): 0.47 J/(g·K); Cp(gas): 0.33 J/(g·K), at 25℃
Sensitive Air Sensitive
Merck 13,2022
Exposure limits PC-TWA:2 mg/m3
Stability Stable. Incompatible with acids. Absorbs carbon dioxide from the air.
InChI 1S/Cs.H2O/h;1H2/q+1;/p-1
InChIKey HUCVOHYBFXVBRW-UHFFFAOYSA-M
SMILES [OH-].[Cs+]
CAS DataBase Reference 21351-79-1(CAS DataBase Reference)
FDA UNII 458ZFZ6235
NIST Chemistry Reference Cesium hydroxide(21351-79-1)
EPA Substance Registry System Cesium hydroxide (21351-79-1)
UNSPSC Code 12352302
NACRES NA.23

SAFETY

Risk and Safety Statements

Symbol(GHS)  Corrosion (GHS05)Exclamation Mark (GHS07)Health Hazard (GHS08)
GHS05,GHS07,GHS08
Signal word  Danger
Hazard statements  H302-H314-H318-H361-H373
Precautionary statements  P264-P270-P260-P280-P201-P202-P301+P312-P330-P301+P330+P331-P303+P361+P353-P363-P304+P340-P310-P305+P351+P338-P308+P313-P314-P405-P501
Hazard Codes  C
Risk Statements  22-35-34
Safety Statements  26-36/37/39-45-37/39-27-28
OEB B
OEL TWA: 2 mg/m3
RIDADR  UN 2682
WGK Germany  3
3
TSCA  TSCA listed
HazardClass  8
PackingGroup  II
HS Code  28259090
Storage Class 8A - Combustible corrosive hazardous materials
Hazard Classifications Acute Tox. 4 Oral
Skin Corr. 1B
Hazardous Substances Data 21351-79-1(Hazardous Substances Data)
Toxicity LD50 i.p. in rats: 100 mg/kg (Cochran)
REACH Registrations Active
NFPA 704
0
3 0

Cesium hydroxide price More Price(36)

Manufacturer Product number Product description CAS number Packaging Price Updated Buy
Sigma-Aldrich 232041 Cesium hydroxide solution 50 wt. % in H2O, 99.9% trace metals basis 21351-79-1 10g $58.6 2026-04-30 Buy
Sigma-Aldrich 232041 Cesium hydroxide solution 50 wt. % in H2O, 99.9% trace metals basis 21351-79-1 50g $154 2026-04-30 Buy
Strem Chemicals 93-5520 Cesium hydroxide, 50% aqueous solution (99.9%-Cs) (99.9%-Cs) 21351-79-1 25g $55 2026-04-30 Buy
Strem Chemicals 93-5520 Cesium hydroxide, 50% aqueous solution (99.9%-Cs) (99.9%-Cs) 21351-79-1 100g $163 2026-04-30 Buy
GFS CHEMICALS 21483 CESIUM HYDROXIDE, 99%, 50% AQUEOUS SOLUTION 21351-79-1 250G $225.8 2026-06-03 Buy
Product number Packaging Price Buy
232041 10g $58.6 Buy
232041 50g $154 Buy
93-5520 25g $55 Buy
93-5520 100g $163 Buy
21483 250G $225.8 Buy

Cesium hydroxide Chemical Properties,Uses,Production

Description

Cesium Hydroxide, as a water-soluble source of cesium, is typically found in any of several hydrate forms. Its applications are relatively limited due to its volatility and high basicity – corroding glass – as well as the high cost of cesium extraction. These applications include use as an electrolyte in alkaline batteries, particularly below the freezing point of water, in color photography, and as a catalyst for synthesis of organics such as phenylacetylene and polymers. Furthermore, it also finds use as a precursor in the manufacture of cesium salts.

Chemical Properties

Caesium hydroxide (CsOH) is a colorless-to-yellow crystalline compound that is commonly used in aqueous solution. It is a strongly hygroscopic base and rapidly corrodes the surfaces of semiconductor materials such as silicon. Although CsOH was once regarded as one of the strongest conventional bases, many compounds, including n-butyllithium, caesium hydride, and sodium amide, exhibit significantly greater protonic basicity than CsOH.

Physical properties

White to yellowish fused crystalline mass; highly deliquescent; very alkaline; density 3.68 g/cm3; melts 272°C; highly soluble in water; soluble in ethanol; aqueous solution is very alkaline.

Uses

Cesium hydroxide is used in the preparation of porous cesium titanosilicates, which are potential ion-exchange materials utilized for radioactive wastes cleaning purpose. It is also involved in the preparation of other cesium salts. Further, it is used as an electrolyte in alkaline storage batteries and as a catalyst in organic synthesis. In addition to this, it is used in color photography.

Definition

ChEBI: Caesium hydroxide is an alkali metal hydroxide and a caesium molecular entity.

Application

Cesium hydroxide also exerts unusual effects in organic reactions, such as the controlled alkylation of amines. In this instance, the cesium ion itself is explicitly involved in the reaction. The hydroxide base promotes an alkylation of a primary amine, while the Cs+ ion weakly coordinates to the amine such that further alkylation is inhibited, preventing formation of dialkyl and trialkyl amines.
Cesium hydroxide solution is used in industrial catalysis. Cesium acts as apromoter e.g. in the production of polyols. Polyols are important raw materials for the production of polyurethane foams. Their synthesis profits from use of cesium hydroxide as base catalyst. In polyol synthesis isomerization of the starting material propylene oxide is an adverse side reaction eventually leading to chain termination in the polymerization with polyisocyanate. The tendency of polyols to undergo isomerization is minimized when using cesium hydroxide, as isomerization tendency decreases in the order Li > Na > K > Rb > Cs.

Preparation

Cesium hydroxide is prepared by electrolysis of cesium salts to obtain cesium metal, which then reacts with water to yield hydroxide. It also is prepared by the action of barium hydroxide with an aqueous solution of cesium sulfate.

General Description

Cesium hydroxide is a colorless to yellow crystalline solid. Harmful to skin and eyes. Used in electric storage batteries.

Air & Water Reactions

Dilution with water may generate enough heat to cause steaming or spattering.

Reactivity Profile

CESIUM HYDROXIDE,SOLUTION neutralizes acids exothermically to form salts plus water. Reacts with certain metals (such as aluminum and zinc) to form oxides or hydroxides of the metal and generate gaseous hydrogen. May initiate polymerization reactions in polymerizable organic compounds, especially epoxides. May generate flammable and/or toxic gases with ammonium salts, nitrides, halogenated organics, various metals, peroxides, and hydroperoxides. May serve as a catalyst. Reacts when heated above about 84°C with aqueous solutions of reducing sugars other than sucrose, to evolve toxic levels of carbon monoxide [Bretherick, 5th Ed., 1995].

Hazard

A poison. Skin, eye, and upper respiratory tract irritant.

Health Hazard

TOXIC; inhalation, ingestion or skin contact with material may cause severe injury or death. Contact with molten substance may cause severe burns to skin and eyes. Avoid any skin contact. Effects of contact or inhalation may be delayed. Fire may produce irritating, corrosive and/or toxic gases. Runoff from fire control or dilution water may be corrosive and/or toxic and cause pollution.

Fire Hazard

Non-combustible, substance itself does not burn but may decompose upon heating to produce corrosive and/or toxic fumes. Some are oxidizers and may ignite combustibles (wood, paper, oil, clothing, etc.). Contact with metals may evolve flammable hydrogen gas. Containers may explode when heated.

Flammability and Explosibility

Non flammable

Safety Profile

Poison by intraperitoneal route. Moderately toxic by ingestion. A powerful caustic. A corrosive skin and eye irritant. See also CESIUM.

Potential Exposure

Cesium hydroxide may be used as a raw material for other cesium salts; such as the chloride which in turn may be used to produce cesium metal. Cesium metal is used in electronic devices.

First aid

If this chemical gets into the eyes, remove anycontact lenses at once and irrigate immediately for at least30 min, occasionally lifting upper and lower lids. Seek medical attention immediately. If this chemical contacts theskin, remove contaminated clothing and wash immediatelywith soap and water. Seek medical attention immediately. Ifthis chemical has been inhaled, remove from exposure,begin rescue breathing (using universal precautions,Cesium hydroxide 591including resuscitation mask) if breathing has stopped andCPR if heart action has stopped. Transfer promptly to amedical facility. When this chemical has been swallowed,get medical attention. If victim is conscious, administerwater or milk. Do not induce vomiting.

storage

Color Code—White: Corrosive or Contact Hazard:Store separately in a corrosion-resistant location. Prior toworking with cesium hydroxide you should be trained on itsproper handling and storage. Cesium hydroxide should bestored in silver or platinum away from air because it reactsviolently with oxygen. Store in tightly closed containers ina cool, well-ventilated area away from moisture and incompatible materials listed above.

Shipping

UN2682 Cesium hydroxide, Hazard class: 8; Labels: 8-Corrosive material. UN2681 Cesium hydroxide, solution, Hazard class: 8; Labels: 8-Corrosive material

Incompatibilities

Cesium hydroxide is the strongest base known. Keep away from all acids. It must be stored in silver or platinum and out of contact with air because of its reactivity with glass. CsOH causes the generation of considerable heat in contact with water or moisture. Contact with many organic compounds, many metals (i.e., aluminum, lead, tin, zinc), glass, oxygen, or carbon dioxide causes a violent reaction.

References

https://www.alfa.com/en/catalog/B22480/
https://www.alfa.com/en/catalog/013233/
https://en.wikipedia.org/wiki/Caesium_hydroxide
https://pubchem.ncbi.nlm.nih.gov/compound/Cesium_hydroxide#section=Use-and-Manufacturing
http://www.chemicalland21.com/industrialchem/inorganic/CESIUM%20HYDROXIDE.htm
https://www.americanelements.com/cesium-hydroxide-hydrate-12260-45-6

Cesium hydroxide Preparation Products And Raw materials

Raw materials

Preparation Products

Global( 115)Suppliers
Supplier Tel Email Country ProdList Advantage
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Beijing innoChem Science & Technology Co.,Ltd. 400-810-7969 010-59572699 ningzi.li@inno-chem.com.cn China 6122 55
Cesium hydroxide, 99.9% metals basis, 50 wt. % solution in water CESIUM HYDROXIDE, 99%, 50 WT. % SOLUTION IN WATER CESIUM HYDROXIDE, 50% AQUEOUS SOLUTION Cesium hydroxide, 50 wt% solution in water, for analysis, 99% CESIUM HYDROXIDE, 99% 50% AQUEOUS SOLUTION CESIUM HYDROXIDE, 99.9% 50% AQUEOUS SOLUTION Cesiumhydroxide,50%aqueoussolution(99.9%-Cs) CESIUM HYDROXIDE, 50% AQUEOUS SOLUTION: 99.9% (METALS BASIS) Cesium hydroxide,99%,for analysis,50 wt% solution in water Cesium hydroxide, anhydrous Cesium hydroxide, 99%, 50 WT% solution in water, for analysis Cesium hydoxide Caesium Hydroxide, 50% Aqueous Solution Cesium hydroxide, 50% w/w aq. soln., 99% (metals basis) Cesium hydroxide, 50% w/w aq. soln., 99.9% (metals basis) Cesium hydroxide, ca 50 wt% aq. soln. Cesium Hydroxide, 50% Aqueous Caesium Hydroxide, 50% Aqueous Solution 99.9% Caesium Hydroxide 99.9% CesiuM hydroxide, for analysis, 50 wt% solution in water, (trace Metal basis) CesiuM hydroxide, 99.9%, (trace Metal basis), for analysis, 50 wt% solution in water CesiuM hydroxide, 50 wt% solution in water, for analysis, 99% 100GR CesiuM hydroxide, 50 wt% solution in water, for analysis, 99% 500GR Cesium hydroxide Cesium hydroxide, for analysis, 50 wt% solution in water, (trace metal basis), 99.9% Cesium hydroxide - 50% solution in water CesiuM hydroxide, 50 wt.% solution in H2O Cesium hydroxide solution, 50 wt. % in water, 99.9% trace metals basis Cesium hydroxide solution, 50 wt. % in water, 99% trace metals basis Caesium hydoxide caesiumhydroxide,solution CesiuM hydroxide solution 50 wt. % in H2O, 99% trace Metals basis (purity deterMined on Metals basis) CesiuM hydroxide solution 50 wt. % in H2O, 99.9% trace Metals basis CESIUM HYDROXIDE, 99%, 50% AQUEOUS SOLUTIONCESIUM HYDROXIDE, 99%, 50% AQUEOUS SOLUTIONCESIUM HYDROXIDE, 99%, 50% AQUEOUS SOLUTIONCESIUM HYDROXIDE, 99%, 50% AQUEOUS SOLUTION CESIUM HYDROXIDE, 99.9%, 50% AQUEOUS SOLUTIONCESIUM HYDROXIDE, 99.9%, 50% AQUEOUS SOLUTIONCESIUM HYDROXIDE, 99.9%, 50% AQUEOUS SOLUTIONCESIUM HYDROXIDE, 99.9%, 50% AQUEOUS SOLUTION Cesium hydroxide (Cs(OH)) Cesium hydroxide dimer cesiumhydroxide(cs(oh)) cesiumhydroxidedimer Cesium hydroxide 21351-79-1 Cesium hydroxide 50 wt% solution in water Cesium hydroxide CESIUM HYDROXIDE 50% SOLUTION 99.9% CsOH 21351-79-1 HCsO Inorganic Bases Synthetic Reagents Inorganic Bases Materials Science Metal and Ceramic Science Synthetic Reagents Cesium SaltsChemical Synthesis Inorganic Bases Metal and Ceramic Science Salts Synthetic Reagents Cesium Salts