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Metals, alloys and elements

Cesium

Also known as Caesium, Cesium-133, Cesium, elemental

CAS 7440-46-2Formula CsMolar mass 132.91 g/molEC 231-155-4
GHS signal word: Danger. Pictograms: Flammable, Corrosive 42 suppliers listed
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Element with atomic number and standard atomic weight

Key facts

What buyers check first

All properties
Appearance
Silvery white, soft, ductile metal
Melting point
29 °C
Boiling point
685 °C
Density
1892 kg/m³ (solid at 17 °C), 1827 kg/m³ (liquid at 40 °C)
Solubility
Soluble in liquid ammonia
HS code
280519
Category
Metals, alloys and elements
UN number
UN 1407
Illustrative photo, assorted laboratory chemical bottles and jars on a laboratory bench
Typical packagingIllustrative packaging image, not the actual product

What is Cesium?

Plain description, key identifiers and synonyms

Caesium atom is an alkali metal atom.

Cesium is a chemical element with symbol Cs and atomic number 55.

Identifiers

Registry numbers, names and line notations, tap to copy

IUPAC name
cesium
CAS number
7440-46-2 CAS number cross-checked
EC number
231-155-4
Molecular formula
Cs
UNII
1KSV9V4Y4I
MDL number
MFCD00134037
InChIKey
TVFDJXOCXUVLDH-UHFFFAOYSA-N
InChI
InChI=1S/Cs
SMILES (canonical and isomeric)
[Cs]

Synonyms

  • Caesium
  • Cesium-133
  • Cesium, elemental
  • Caesium 133
  • Caesium-133
  • Cesium 133
  • Cs
  • caesium atom
  • Cesium metal
  • cesio
  • Cesium Standard: Cs @ 1000 microg/mL in 5% HNO3
  • Cesium Standard: Cs @ 10000 microg/mL in 5% HNO3
  • Zaesium
  • Cesium element
  • Cesium atom
  • Element Cesium
  • Element:Cesium
  • Atomic Cesium
  • Element-Cs
  • Element:Cs
  • Cesium (atomic)
  • Cesium (element)
  • Cs (element)
  • 133Cs isotope
  • Isotope:133Cs
Show all 38 synonyms
  • Cs Standard Solution
  • 133Cs (isotope)
  • Cesium-133 isotope
  • Isotope:Cesium-133
  • 55Cs
  • Cesium, purum, >=99.5%
  • Ion Chromatography Cation Std Caesium
  • Cesium, Cesium-133, Caesium, Casium
  • AA standard CESIUM 1M HNO3 10000 ppm
  • Cesium, ingot, >=99.95% trace metals basis
  • Cesium - Cs @ 1000 microg/mL in 5% HNO3
  • Cesium, solid, 99.8% trace metals basis ampoule
  • ICP standard Cesium 2-5% HNO3 1000 microg/mL

Physical and chemical properties

Measured values and descriptors computed from the structure

Physical and chemical properties

Measured values, check the supplier specification for your grade

Appearance
Silvery white, soft, ductile metalexp.
Melting point
29 °Cexp.
Boiling point
685 °Cexp.
Density
1892 kg/m³ (solid at 17 °C), 1827 kg/m³ (liquid at 40 °C)exp.
Solubility
Soluble in liquid ammoniaexp.
Vapour pressure
1.5 × 10⁻⁶ mm Hg at 25 °C (solid)exp.

Values vary by grade. Ask suppliers for the COA or TDS of the batch you buy.

Computed descriptors

Calculated from the structure, useful for screening and formulation

Molecular weight
132.91 g/molcalc.
Exact mass
132.9055 Dacalc.
LogP (octanol/water)
-0.38calc.
Topological polar surface area
0 Ųcalc.
Hydrogen bond donors
0calc.
Hydrogen bond acceptors
0calc.
Rotatable bonds
0calc.
Heavy atoms
1calc.
Rings
0calc.
Aromatic rings
0calc.
Fraction sp3 carbons
0calc.
Formal charge
0calc.
Stereocentres
0calc.

Calculated for screening. Confirm critical figures with the supplier.

Safety and hazards

GHS classification summary, not a safety data sheet

GHS signal word
Danger
GHS02: Flammable
Flammable
GHS05: Corrosive
Corrosive

Hazard statements

  • H260In contact with water releases flammable gases which may ignite spontaneously.
  • H314Causes severe skin burns and eye damage.
  • H318Causes serious eye damage.
Precautionary statements (19)
  • P223Do not allow contact with water.
  • P231 + P232Handle and store contents under inert gas. Protect from moisture.
  • P260Do not breathe dust, fume, gas, mist, vapours or spray.
  • P264Wash skin thoroughly after handling.
  • P264 + P265Wash skin thoroughly after handling. Do not touch eyes.
  • P280Wear protective gloves, protective clothing, eye protection and face protection.
  • P301 + P330 + P331If swallowed: Rinse mouth. Do not induce vomiting.
  • P302 + P335 + P334If on skin: Brush off loose particles from skin. Immerse in cool water or wrap in wet bandages.
  • P302 + P361 + P354If on skin: Take off immediately all contaminated clothing. Immediately rinse with water for several minutes.
  • P304 + P340If inhaled: Remove person to fresh air and keep comfortable for breathing.
  • P305 + P354 + P338If in eyes: Immediately rinse with water for several minutes. Remove contact lenses, if present and easy to do. Continue rinsing.
  • P316Get emergency medical help immediately.
  • P317Get medical help.
  • P321Specific treatment (see supplemental first aid instructions on the label).
  • P363Wash contaminated clothing before reuse.
  • P370 + P378In case of fire: Use appropriate media to extinguish.
  • P402 + P404Store in a dry place. Store in a closed container.
  • P405Store locked up.
  • P501Dispose of contents and container in accordance with local regulations.
UN number
UN 1407
Transport hazard class
4.3
Packing group
I

GHS classification summary, not a safety data sheet (SDS). Classifications can differ by supplier, grade and concentration. Always check the supplier's SDS.

Full safety data and first aid

Cesium suppliers

Sponsored listings first, then the documented ranking: membership, verification, replies, completeness, freshness and ratings

All 42 suppliers
30 of 30 offers

Suppliers marked Unclaimed profile have not claimed their profile yet. They are not verified by CompoundList, their offers are price on request and details may have changed, so please confirm them with the supplier. Company representatives can claim a profile with a business email on the company's own website domain. Our team verifies each claim and sends the result by email.

Where suppliers are based

42 suppliers in 16 countries

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Cesium price

Indicative price range per kg from live supplier offers

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Uses and applications

What the substance is used for, by industry and function

Carbon dioxide purification, ferrous and nonferrous metallurgy as a scavenger of gases and other impurities, magnetohydrodynamic power generation, ion engines.

Specialty, high-density drilling fluids used in the global oil and gas exploration industry. Cesium is also used in DNA separation techniques, infrared detectors, night vision devices, photoelectric cells, and traffic controls.

In photovoltaic cells, as a "getter" in vacuum tubes, in photoemitter devices, scintillation counters. Adsorbent in CO2 purifn, scavenger of gases and impurities in metallurgy. For doping catalysts.

Magnesium is used to obtain cesium metal from cesium hydroxide, cesium carbonate, or cesium aluminate. Vacuum redistillation at low temperature is used for final purification of the cesium metal if required.

Use classes: Radionuclides.

How it is made

Cesium halides can readily be reduced using calcium or barium, but not magnesium. Purified cesium chloride and calcium in roughly equal proportions are heated together to 700-800 °C under vacuum or in an atmosphere of an inert gas such as argon or helium, and 90-95% of the cesium is distilled as metal, although lower temperatures (300-400 °C) and higher vacuum achieve the same result but with higher purity. Magnesium is used to obtain cesium metal from cesium hydroxide, cesium carbonate, or cesium aluminate.

Read more

Vacuum redistillation at low temperature is used for final purification of the cesium metal if required.

Treatment of pollucite with hydrochloric acid at elevated temperature produces a solution of chlorides of cesium, aluminum, and alkali metals, which is separated from the silica residue. The cesium is precipitated as mixed chloride with lead, antimony, or tin. Hydrolysis precipitates the auxiliary metal. Alternatives are precipitation with hydrogen sulfide or recovery of cesium by solvent extraction from the leach liquor or ion exchange from cesium chloride solution.

Alkaline decomposition can be carried out either by mixing ore with lime and calcium chloride and heating to 800 to 900 °C followed by leaching of the residue or by heating pollucite with sodium chloride and soda ash to 600 to 800 °C followed by leaching. In both cases, solutions of impure cesium chloride result.

Regulatory status

Inventories, regulations and trade controls that list this substance

United States

  • TSCA inventory (USA)
    Status: Active in US commerce

HS code and trade data

Customs classification and reported world trade statistics

Global trade

World import and export statistics for the HS code Cesium is traded under.

HS 2805.19Indicative HS code

Alkali or alkaline-earth metals, other

World exports in 2024
$574M
−11.1% vs 2023, imports $558M
2019 to 2024
Top exporters
  1. France * partner reported58.4%
  2. China19.1%
  3. Germany13.1%
Top importers
  1. Germany59.4%
  2. United States7.9%
  3. France * partner reported4.7%

* Partner reported figures, a lower bound.

Reported customs values in USD, not prices.Full trade data

The HS code shown for Cesium is indicative (it was assigned by structure rules). Confirm the classification with your customs broker before shipping.

Frequently asked questions

Quick answers about Cesium, based on the data on this page

What is Cesium?

Caesium atom is an alkali metal atom.

What is the CAS number of Cesium?

The CAS registry number of Cesium is 7440-46-2.

What is the molecular formula and weight of Cesium?

The molecular formula of Cesium is Cs and its molar mass is 132.91 g/mol.

What is Cesium used for?

Carbon dioxide purification, ferrous and nonferrous metallurgy as a scavenger of gases and other impurities, magnetohydrodynamic power generation, ion engines. Specialty, high-density drilling fluids used in the global oil and gas exploration industry.

Is Cesium hazardous?

Cesium carries the GHS signal word "Danger". Main hazards: in contact with water releases flammable gases which may ignite spontaneously, causes severe skin burns and eye damage, causes serious eye damage. This summary is not an SDS, always read the supplier safety data sheet.

What is the HS code of Cesium?

Cesium is usually classified under HS code 280519 (Alkali or alkaline-earth metals, other). This is indicative, confirm it with your customs broker before shipping.

Where can I buy Cesium?

CompoundList lists 42 suppliers of Cesium in United States, China, Germany, Spain and 12 more. Send one free request to get and compare quotes. Your contact details stay private until you accept a quote.

Where can I buy Cesium in India?

2 suppliers in India list Cesium on CompoundList. Filter the suppliers list by country and send a request to compare prices, grades and delivery times.

What is the price of Cesium?

Suppliers quote Cesium on request because prices depend on grade, purity, quantity and destination. A free request on CompoundList gets you several quotes to compare.

Guides for buyers

Practical guides that help when you source, ship or handle Cesium

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Data last updated 7 Oct 2026. Details may have changed, please confirm them with the supplier. Report an error on this page
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