Chromium Trioxide

1Identification

Name

Chromium Trioxide

IUPAC name

trioxochromium

CAS number

1333-82-0

EC number

215-607-8

Molecular formula

CrO3

Molecular weight

99.994 g/mol

InChIKey

WGLPBDUCMAPZCE-UHFFFAOYSA-N

SMILES

O=[Cr](=O)=O

PubChem CID

14915

Synonyms

Chromium trioxide, Chromium(VI) oxide, trioxochromium, CrO3, Chromtrioxid, Monochromium trioxide, CHROMIC TRIOXIDE, Chromsaeureanhydrid, Anhydride chromique, Chromium(6+) oxide, Chromia (CrO3), Chroomtrioxyde, Chromium(6+) trioxide, Anidride cromica

Recommended uses

• Used in chromium plating, copper stripping, and aluminum anodizing; also used to inhibit corrosion, to develop photographs, to purify oil and acetylene, to harden microscopic preparations, and to oxidize organic chemicals; [HSDB] Used in sulfuric acid as a photoresist stripper; [CSH, p. 49] Also used as a wood preservative; [ACGIH]
  Haz-Map, Information on Hazardous Chemicals and Occupational Diseases
• Aluminum Producing [Category: Industry] Electroplating [Category: Plate] Petroleum Production and Refining [Category: Industry] Semiconductor Manufacturing [Category: Industry] Applying Wood Preservatives [Category: Other] Photographic Processing [Category: Other]
  Haz-Map, Information on Hazardous Chemicals and Occupational Diseases
• Applying metallic patinas [Category: Hobbies]
  Haz-Map, Information on Hazardous Chemicals and Occupational Diseases
• Surface modifier Processing aids, specific to petroleum production Intermediate Chelating agent Etching agent Adhesion/cohesion promoter Catalyst Not Known or Reasonably Ascertainable Corrosion inhibitor Cleaning agent Plating agent Other
  EPA Chemical Data Reporting (CDR)
• Catalyst
  EPA Chemical Data Reporting (CDR)

Description

• Chromium trioxide, anhydrous appears as a dark purplish red solid. Under prolonged exposure to fire or heat the containers may explode. Highly toxic. A confirmed human carcinogen.
  CAMEO Chemicals
• Chromium trioxide is a chromium oxide composed of a single chromium bound (oxidation state +6) to three oxygens; the acidic anhydride of chromic acid.
  ChEBI
• Chromium Trioxide is a dark red to brown colored, crystalline, inorganic compound that emits toxic chromium fumes upon heating. Chromium trioxide is highly corrosive and is a strong oxidizing agent. This substance is mainly used in the production of wood preservatives and organic chemicals, but is also used in metal finishing and chrome plating and as a corrosion inhibitor. Chromium trioxide primarily affects the nose, throat and lungs causing ulcerations, shortness of breath, bronchitis, pneumonia and asthma-like allergy but can also affect the gastrointestinal tract, liver, kidneys and immune system.
  NCI Thesaurus (NCIt)

2Hazard identification

Signal word

Danger

Pictograms

GHS03, GHS05, GHS06, GHS07, GHS08, GHS09

Classification source

European Chemicals Agency (ECHA)

Precautionary statements

Other reported classifications

5 classification records exist across sources. Differences usually reflect purity, physical form or impurities.

Health hazards

• Very irritating to eyes and respiratory tract. Ingestion causes severe gastrointestinal symptoms. Contact with eyes or skin causes burns; prolonged contact produces dermatitis ("chrome sores"). (USCG, 1999)
  CAMEO Chemicals
• · Toxic by ingestion. · Inhalation of dust is toxic. · Fire may produce irritating, corrosive and/or toxic gases. · Contact with substance may cause severe burns to skin and eyes. · Runoff from fire control or dilution water may cause environmental contamination.
  Emergency Response Guidebook (ERG)

Fire hazards

• Behavior in Fire: Containers may explode (USCG, 1999)
  CAMEO Chemicals
• · These substances will accelerate burning when involved in a fire. · May explode from heat or contamination. · Some may burn rapidly. · Some will react explosively with hydrocarbons (fuels). · May ignite combustibles (wood, paper, oil, clothing, etc.). · Containers may explode when heated. · Runoff may create fire or explosion hazard.
  Emergency Response Guidebook (ERG)
• Not combustible but enhances combustion of other substances. Many reactions may cause fire or explosion.
  ILO-WHO International Chemical Safety Cards (ICSCs)

Hazards summary

• CrVI compounds are irritants, sensitizers, and may be corrosive to the skin. CrVI compounds are respiratory tract irritants and may cause pulmonary sensitization. CrVI may cause acute tubular necrosis and liver injury. [ATSDR Case Studies] Highly corrosive to skin; [Quick CPC] Chromium trioxide (chromic acid) is a water-soluble hexavalent chromium compounds. A corrosive substance that can cause injury to the skin, eyes, and respiratory tract; May cause skin sensitization, kidney injury, and asthma after prolonged contact; [ICSC] See Chromium and linked occupational diseases.
  Haz-Map, Information on Hazardous Chemicals and Occupational Diseases

3Composition / information on ingredients

This page describes the pure substance. Commercial products may be solutions or mixtures. Check Section 3 of your supplier's SDS for concentrations and other ingredients.

4First-aid measures

• EYES: First check the victim for contact lenses and remove if present. Flush victim's eyes with water or normal saline solution for 20 to 30 minutes while simultaneously calling a hospital or poison control center. Do not put any ointments, oils, or medication in the victim's eyes without specific instructions from a physician. IMMEDIATELY transport the victim after flushing eyes to a hospital even if no symptoms (such as redness or irritation) develop. SKIN: IMMEDIATELY flood affected skin with water while removing and isolating all contaminated clothing. Gently wash all affected skin areas thoroughly with soap and water.
  CAMEO Chemicals
• General First Aid: · Call 911 or emergency medical service. · Ensure that medical personnel are aware of the material(s) involved, take precautions to protect themselves and avoid contamination. · Move victim to fresh air if it can be done safely. · Administer oxygen if breathing is difficult. · If victim is not breathing: -- DO NOT perform mouth-to-mouth resuscitation; the victim may have ingested or inhaled the substance. -- If equipped and pulse detected, wash face and mouth, then give artificial respiration using a proper respiratory medical device (bag-valve mask, pocket mask equipped with a one-way valve or other device).
  Emergency Response Guidebook (ERG)
• (General first aid procedures) Eye: Irrigate immediately - If this chemical contacts the eyes, immediately wash (irrigate) the eyes with large amounts of water, occasionally lifting the lower and upper lids. Get medical attention immediately. Skin: Soap flush immediately - If this chemical contacts the skin, immediately flush the contaminated skin with soap and water. If this chemical penetrates the clothing, immediately remove the clothing and flush the skin with water. If irritation persists after washing, get medical attention. Breathing: Respiratory support Swallow: Medical attention immediately - If this chemical has been swallowed, get medical attention immediately.
  The National Institute for Occupational Safety and Health (NIOSH)

Symptoms of exposure

• Burning sensation. Sore throat. Cough. Wheezing. Laboured breathing.
  ILO-WHO International Chemical Safety Cards (ICSCs)
• Redness. Pain. Skin burns.
  ILO-WHO International Chemical Safety Cards (ICSCs)
• Redness. Pain. Blurred vision. Severe burns.
  ILO-WHO International Chemical Safety Cards (ICSCs)

5Fire-fighting measures

• Suitable extinguishing media: Use water spray, alcohol-resistant foam, dry chemical or carbon dioxide.
  Hazardous Substances Data Bank (HSDB)
• Advice for firefighters: Wear self-contained breathing apparatus for firefighting if necessary.
  Hazardous Substances Data Bank (HSDB)
• Use water spray to cool unopened containers.
  Hazardous Substances Data Bank (HSDB)

Hazardous combustion products

• Special hazards arising from the substance or mixture: Chromium oxides
  Hazardous Substances Data Bank (HSDB)

6Accidental release measures

Isolation and evacuation

• Excerpt from ERG Guide 141 [Oxidizers - Toxic]: IMMEDIATE PRECAUTIONARY MEASURE: Isolate spill or leak area in all directions for at least 50 meters (150 feet) for liquids and at least 25 meters (75 feet) for solids. LARGE SPILL: Consider initial downwind evacuation for at least 100 meters (330 feet). FIRE: If tank, rail tank car or highway tank is involved in a fire, ISOLATE for 800 meters (1/2 mile) in all directions; also, consider initial evacuation for 800 meters (1/2 mile) in all directions. (ERG, 2024)
  CAMEO Chemicals
• Immediate precautionary measure · Isolate spill or leak area in all directions for at least 50 meters (150 feet) for liquids and at least 25 meters (75 feet) for solids. Large Spill · Consider initial downwind evacuation for at least 100 meters (330 feet). Fire · If tank, rail tank car or highway tank is involved in a fire, ISOLATE for 800 meters (1/2 mile) in all directions; also, consider initial evacuation for 800 meters (1/2 mile) in all directions.
  Emergency Response Guidebook (ERG)

Spill cleanup

• Personal protection: complete protective clothing including self-contained breathing apparatus. Do NOT let this chemical enter the environment. Sweep spilled substance into sealable containers. If appropriate, moisten first to prevent dusting. Carefully collect remainder. Then store and dispose of according to local regulations. Do NOT absorb in saw-dust or other combustible absorbents.
  ILO-WHO International Chemical Safety Cards (ICSCs)
• ACCIDENTAL RELEASE MEASURES: Personal precautions, protective equipment and emergency procedures: Wear respiratory protection. Avoid dust formation. Avoid breathing vapors, mist or gas. Ensure adequate ventilation. Evacuate personnel to safe areas. Avoid breathing dust; Environmental precautions: Prevent further leakage or spillage if safe to do so. Do not let product enter drains. Discharge into the environment must be avoided; Methods and materials for containment and cleaning up: Sweep up and shovel. Contain spillage, and then collect with an electrically protected vacuum cleaner or by wetbrushing and place in container for disposal according to local regulations.
  Hazardous Substances Data Bank (HSDB)
• Isolation and Evacuation: As an immediate precautionary measure, isolate spill or leak area in all directions for at least 50 meters (150 feet) for liquids and at least 25 meters (75 feet) for solids. Large spill: Consider initial downwind evacuation for at least 100 meters (330 feet). Fire: If tank, rail car or tank truck is involved in a fire, ISOLATE for 800 meters (1/2 mile) in all directions; also, consider initial evacuation for 800 meters (1/2 mile) in all directions.
  Hazardous Substances Data Bank (HSDB)
• Cr(VI) cmpd in waste sludge are completely removed by redn by carbon at 600 °C. /Chromium VI/
  Hazardous Substances Data Bank (HSDB)

7Handling and storage

• Provision to contain effluent from fire extinguishing. Separated from combustible substances, reducing agents, bases and food and feedstuffs. Well closed. Store in an area without drain or sewer access.
  ILO-WHO International Chemical Safety Cards (ICSCs)
• Keep container tightly closed in a dry and well-ventilated place. Hygroscopic. Heat sensitive. Storage class (TRGS 510): Strongly oxidizing hazardous materials
  Hazardous Substances Data Bank (HSDB)
• Storage recommendations: Store in a cool, dry, well-ventilated location. Separate from combustible materials, halogens, sulfides, metals.
  Hazardous Substances Data Bank (HSDB)

8Exposure controls / personal protection

Personal protective equipment

• Goggles and respirator. (Special chromic acid filters are available for respirators to prevent inhalation of dust or mist.) (USCG, 1999)
  CAMEO Chemicals
• Eye/face protection: Face shield and safety glasses. Use equipment for eye protection tested and approved under appropriate government standards such as NIOSH (US) or EN 166(EU).
  Hazardous Substances Data Bank (HSDB)
• Skin protection: Handle with gloves.
  Hazardous Substances Data Bank (HSDB)
• 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.
  Hazardous Substances Data Bank (HSDB)

Respirator recommendations

• NIOSH At concentrations above the NIOSH REL, or where there is no REL, at any detectable concentration: (APF = 10,000) Any self-contained breathing apparatus that has a full facepiece and is operated in a pressure-demand or other positive-pressure mode (APF = 10,000) Any supplied-air respirator that has a full facepiece and is operated in a pressure-demand or other positive-pressure mode in combination with an auxiliary self-contained positive-pressure breathing apparatus Escape: (APF = 50) Any air-purifying, full-facepiece respirator with an N100, R100, or P100 filter. Click here for information on selection of N, R, or P filters.
  The National Institute for Occupational Safety and Health (NIOSH)

9Physical and chemical properties

10Stability and reactivity

Reactivity

• CHROMIUM TRIOXIDE is a powerful oxidizing agent. Can react violently upon contact with reducing reagents, including organic matter, leading to ignition or explosion. Dangerously reactive with acetone, alcohols, alkali metals (sodium, potassium), ammonia, arsenic, dimethylformamide, hydrogen sulfide, phosphorus, peroxyformic acid, pyridine, selenium, sulfur, and many other chemicals [Sax, 9th ed., 1996, p. 852]. Noncombustible but can accelerate the burning of combustible materials. Sufficient heat may be generated from the reaction with combustible materials to ignite the mass. Aqueous solutions corrode many metals rapidly.
  CAMEO Chemicals
• Deliquescent. Water soluble, giving acidic solutions.
  CAMEO Chemicals

Incompatible materials and hazardous reactions

• Incompatible materials: Organic materials, Phosphorus, powdered metals.
  Hazardous Substances Data Bank (HSDB)
• Water-reactive.
  Hazardous Substances Data Bank (HSDB)
• Acetylene is oxidized violently.
  Hazardous Substances Data Bank (HSDB)

Chemical stability

• Stable under recommended storage conditions.
  Hazardous Substances Data Bank (HSDB)

11Toxicological information

Target organs

• Blood, respiratory system, liver, kidneys, eyes, skin
  The National Institute for Occupational Safety and Health (NIOSH)

Short-term exposure effects

• The substance is corrosive to the eyes, skin and respiratory tract. Corrosive on ingestion. The substance may cause effects on the kidneys and liver. This may result in tissue lesions.
  ILO-WHO International Chemical Safety Cards (ICSCs)

Long-term exposure effects

• Repeated or prolonged contact may cause skin sensitization. Repeated or prolonged inhalation may cause asthma. Repeated or prolonged inhalation may cause nasal ulceration. This may result in perforation of the nasal septum. The substance may have effects on the kidneys. This may result in kidney impairment. This substance is carcinogenic to humans. Animal tests show that this substance possibly causes toxicity to human reproduction or development.
  ILO-WHO International Chemical Safety Cards (ICSCs)

12Ecological information

Not available in the public sources we compile. Check Section 12 of the supplier's SDS.

13Disposal considerations

• Generators of waste (equal to or greater than 100 kg/mo) containing this contaminant, EPA hazardous waste number D007, must conform with USEPA regulations in storage, transportation, treatment and disposal of waste. /Chromium/
  Hazardous Substances Data Bank (HSDB)
• Product: Burn in a chemical incinerator equipped with an afterburner and scrubber but exert extra care in igniting as this material is highly flammable. Offer surplus and non-recyclable solutions to a licensed disposal company. Contact a licensed professional waste disposal service to dispose of this material. Dissolve or mix the material with a combustible solvent and burn in a chemical incinerator equipped with an afterburner and scrubber; Contaminated packaging: Dispose of as unused product.
  Hazardous Substances Data Bank (HSDB)
• Chemical reduction of concentrated materials to Cr (III) and precipitation by pH adjustment. Precipitates are normally disposed in a chemical waste landfill. Recovery and recycle is a viable alternative to disposal for chromium in plating wastes, tannery wastes, cooling tower blowdown and chemical plant wastes. Recommendable methods: Reduction and precipitation. Not recommendable method: Landfill. Peer-review: Cr (VI) can be removed from solution of low acidity by ion exchange. This can allow recovery of Cr (VI), or the resin can be solidified and disposed of to a landfill. Do not landfill chromium trioxide. Contact with combustible material may cause fire.
  Hazardous Substances Data Bank (HSDB)

14Transport information

UN number: UN 1463

Shipping name

• UN 1463; Chromium trioxide, anhydrous.
  Hazardous Substances Data Bank (HSDB)
• IMO 5.1; Chromic trioxide, anhydrous.
  Hazardous Substances Data Bank (HSDB)

DOT hazard class

• Chromium trioxide, anhydrous
  US Code of Federal Regulations, Hazardous Materials, 49 CFR Part 172
• UN1463
  US Code of Federal Regulations, Hazardous Materials, 49 CFR Part 172
• Div 5.1 Oxidizer (49 eCFR § 173.127)
  US Code of Federal Regulations, Hazardous Materials, 49 CFR Part 172

DOT label

• Oxidizer Poison Corrosive
  CAMEO Chemicals

UN classification

• UN Hazard Class: 5.1; UN Subsidiary Risks: 6.1 and 8; UN Pack Group: II
  ILO-WHO International Chemical Safety Cards (ICSCs)

Emergency Response Guidebook

• 1463 141
  Emergency Response Guidebook (ERG)
• 1755 154(acid solution)
  The National Institute for Occupational Safety and Health (NIOSH)

How DOT hazard classes work →

15Regulatory information

• ... Substances for which a Federal Register notice has been published that included consideration of the serious health effects, including cancer, from ambient air exposure to the substance. Chromium is included on this list. /Chromium/
  Hazardous Substances Data Bank (HSDB)
• Toxic pollutant designated pursuant to section 307(a)(1) of the Federal Water Pollution Control Act and is subject to effluent limitations. /Chromium and compounds/
  Hazardous Substances Data Bank (HSDB)
• D007; A solid waste containing chromium may or may not become characterized as a hazardous waste when subjected to the Toxicity Characteristic Leaching Procedure listed in 40 CFR 261.24, and if so characterized, must be managed as a hazardous waste. /Chromium/
  Hazardous Substances Data Bank (HSDB)

Overview of SDS regulations (OSHA HazCom, WHMIS, REACH/CLP) →

16Other information

Compiled from PubChem CID 14915 and the sources it aggregates (attributed inline). Data retrieved 2026-10-12. This summary describes the pure substance and is not a supplier SDS.