Potassium Hydroxide

1Identification

Name

Potassium Hydroxide

IUPAC name

potassium hydroxide

CAS number

1310-58-3

EC number

215-181-3

Molecular formula

HKO

Molecular weight

56.106 g/mol

InChIKey

KWYUFKZDYYNOTN-UHFFFAOYSA-M

SMILES

[OH-].[K+]

PubChem CID

14797

Synonyms

POTASSIUM HYDROXIDE, Caustic potash, Potash lye, Potassium hydrate, Hydroxyde de potassium, Potassa, Potasse caustique, Caustic-potash, Kali causticum, Cyantek CC 723, Potassium hydroxide (K(OH)), Kaliumhydroxid, Potassio (idrossido di), Potassium (hydroxyde de)

Recommended uses

• CIR ingredient: Potassium Hydroxide
  Cosmetic Ingredient Review (CIR)
• Used to make liquid soaps; it is also used in paint, varnish removers, and drain cleaners; it is used in electroplating, photoengraving, and lithography. [ACGIH] Used as a wet etchant in semiconductor manufacturing at standard concentrations of 50% or 10%; [CSH, p. 46]
  Haz-Map, Information on Hazardous Chemicals and Occupational Diseases
• Acid and Alkali Cleaning of Metals [Category: Clean] Electroplating [Category: Plate] Semiconductor Manufacturing [Category: Industry] Battery Manufacturing [Category: Industry] Photographic Processing [Category: Other]
  Haz-Map, Information on Hazardous Chemicals and Occupational Diseases
• Ion exchange agent Catalyst Corrosion inhibitor Not Known or Reasonably Ascertainable Soil amendments (fertilizers) Cleaning agent Absorbent Oxidizing agent Surface modifier Processing aids, specific to petroleum production Intermediate Chelating agent Etching agent Adhesion/cohesion promoter Freeze-thaw additive Lubricating agent Other Flavoring and nutrient Anti-adhesive/cohesive Anti-freeze agent Conductive agent Fuel agents pH regulating agent Plating agent Abrasives Chemical reaction regulator Semiconductor and photovoltaic agent Surfactant (surface active agent) Processing aids not otherwise specified
  EPA Chemical Data Reporting (CDR)
• Solvent Anti-adhesive/cohesive Anti-freeze agent Other Lubricating agent Processing aids not otherwise specified Surfactant (surface active agent) Chemical reaction regulator Fuel agents pH regulating agent Cleaning agent Ion exchange agent Not Known or Reasonably Ascertainable Corrosion inhibitor Soil amendments (fertilizers) Etching agent Processing aids, specific to petroleum production Intermediate
  EPA Chemical Data Reporting (CDR)

Use categories: EPA Safer Chemical Functional Use Classes -> Processing Aids and Additives · Safer Chemical Classes -> Green circle - The chemical has been verified to be of low concern · Food additives · Food Additives -> ACIDITY_REGULATOR -> JECFA Functional Classes

Description

• Potassium hydroxide, solution appears as an clear aqueous solution. Corrosive to metals and tissue. Noncombustible. Used in chemical manufacturing, petroleum refining, cleaning compounds.
  CAMEO Chemicals
• Potassium hydroxide, [dry solid, flake, bead, or granular] appears as a white solid. Corrosive to metals and tissue. Used in soap manufacture, bleach, as an electrolyte in alkaline batteries, and as a food additive.
  CAMEO Chemicals
• Potassium hydroxide is an alkali metal hydroxide.
  ChEBI

2Hazard identification

Signal word

Danger

Pictograms

GHS05, GHS07

Classification source

Regulation (EC) No 1272/2008 of the European Parliament and of the Council

Precautionary statements

Other reported classifications

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

Health hazards

• Causes severe burns of eyes, skin, and mucous membranes. (USCG, 1999)
  CAMEO Chemicals
• · TOXIC and/or CORROSIVE; 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. · Fire may produce irritating, corrosive and/or toxic gases. · Runoff from fire control or dilution water may be corrosive and/or toxic and cause environmental contamination.
  Emergency Response Guidebook (ERG)

Fire hazards

• Excerpt from ERG Guide 154 [Substances - Toxic and/or Corrosive (Non-Combustible)]: 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.). Corrosives in contact with metals may evolve flammable hydrogen gas. Containers may explode when heated. For electric vehicles or equipment, ERG Guide 147 (lithium ion or sodium ion batteries) or ERG Guide 138 (sodium batteries) should also be consulted. (ERG, 2024)
  CAMEO Chemicals
• · 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.). · Corrosives in contact with metals may evolve flammable hydrogen gas. · Containers may explode when heated. · For electric vehicles or equipment, GUIDE 147 (lithium ion or sodium ion batteries) or GUIDE 138 (sodium batteries) should also be consulted.
  Emergency Response Guidebook (ERG)
• Not combustible. Contact with moisture or water may generate sufficient heat to ignite combustible materials. Risk of fire and explosion on contact with incompatible substances. See Chemical Dangers.
  ILO-WHO International Chemical Safety Cards (ICSCs)

Hazards summary

• Liquid causes second or third degree burns after short contact. [CHRIS] Potassium hydroxide 30-70% is highly corrosive to skin; [Quick CPC] A corrosive substance that can cause pulmonary edema; [ICSC] See Sodium hydroxicde.
  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

• (Act quickly]) EYES: flush with water for at least 15 min. SKIN: flush with water, then rinse with dilute vinegar (acetic acid). INGESTION: give water and milk. Do NOT induce vomiting. Call physician at once, even when injury seems to be slight. (USCG, 1999)
  CAMEO Chemicals
• 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: Water flush immediately - If this chemical contacts the skin, immediately flush the contaminated skin with water. If this chemical penetrates the clothing, immediately remove the clothing and flush the skin with water. Get medical attention promptly. 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

• Cough. Sore throat. Burning sensation. Shortness of breath.
  ILO-WHO International Chemical Safety Cards (ICSCs)
• Redness. Pain. Serious skin burns. Blisters.
  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)
• Wear self-contained breathing appartus for firefighting if necessary.
  Hazardous Substances Data Bank (HSDB)

Hazardous combustion products

• Gives off hydrogen by reaction with metals.
  Hazardous Substances Data Bank (HSDB)

6Accidental release measures

Isolation and evacuation

• Excerpt from ERG Guide 154 [Substances - Toxic and/or Corrosive (Non-Combustible)]: 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. SPILL: Increase the immediate precautionary measure distance, in the downwind direction, as necessary. 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. Spill · For highlighted materials: see Table 1 - Initial Isolation and Protective Action Distances. · For non-highlighted materials: increase the immediate precautionary measure distance, in the downwind direction, as necessary. 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: chemical protection suit including self-contained breathing apparatus. Do NOT let this chemical enter the environment. Sweep spilled substance into covered plastic containers. Carefully collect remainder. Then store and dispose of according to local regulations.
  ILO-WHO International Chemical Safety Cards (ICSCs)
• 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...
  Hazardous Substances Data Bank (HSDB)
• Pick up and arrange disposal without creating dust. Sweep up and shovel. Keep in suitable, closed containers for disposal.
  Hazardous Substances Data Bank (HSDB)
• Prevent further leakage or spillage if safe to do so. Do not let product enter drains. Discharge into the environment must be avoided.
  Hazardous Substances Data Bank (HSDB)

7Handling and storage

• Separated from food and feedstuffs, strong acids and metals. Store only in original container. Dry. 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. Absorbs carbon dioxide (CO2) form air. Air sensitive. Strongly hygroscopic. Storage class (TRGS 510): Non-combustible, corrosive hazardous materials.
  Hazardous Substances Data Bank (HSDB)

8Exposure controls / personal protection

Personal protective equipment

• Wide-brimmed hat and close-fitting safety goggles equipped with rubber side shields; long-sleeved cotton shirt or jacket with buttoned collar and buttoned sleeves; rubber or rubber-coated canvas gloves. (Shirt sleeves should be buttoned over the gloves so that any spilled material will run down the outside.) Rubber safety-toe-shoes or boots and cotton coveralls. (Trouser cuffs should be worn outside of boots.) Rubber apron. (USCG, 1999)
  CAMEO Chemicals
• Excerpt from NIOSH Pocket Guide for Potassium hydroxide: Skin: PREVENT SKIN CONTACT - Wear appropriate personal protective clothing to prevent skin contact. Eyes: PREVENT EYE CONTACT - Wear appropriate eye protection to prevent eye contact. Wash skin: WHEN CONTAMINATED - The worker should immediately wash the skin when it becomes contaminated. Remove: WHEN WET OR CONTAMINATED - Work clothing that becomes wet or significantly contaminated should be removed and replaced. Change: DAILY - Workers whose clothing may have become contaminated should change into uncontaminated clothing before leaving the work premises.
  CAMEO Chemicals
• Wear appropriate personal protective clothing to prevent skin contact.
  Hazardous Substances Data Bank (HSDB)
• Wear appropriate eye protection to prevent eye contact.
  Hazardous Substances Data Bank (HSDB)

Respirator recommendations

• Important additional information about respirator selection
  The National Institute for Occupational Safety and Health (NIOSH)

9Physical and chemical properties

10Stability and reactivity

Reactivity

• POTASSIUM HYDROXIDE, SOLUTION is a strong base dissolved in water. Reacts exothermically with all acids. Slowly dissolves glass. Attacks aluminum and zinc to generate flammable hydrogen gas. Ignited a polyethylene container liner when mixed with potassium persulfate by release of heat and oxygen [MCA Case History 1155. 1955].
  CAMEO Chemicals
• POTASSIUM HYDROXIDE absorbs moisture readily forming caustic solution that attacks aluminum and zinc. A piece of potassium hydroxide causes liquid chlorine dioxide to explode [Mellor 2:289. 1946-47]. 1,2-dichloroethylene and potassium hydroxide forms chloroacetylene, which is explosive and spontaneously flammable in air. It is highly toxic [Rutledge 1968. p. 134]. A reaction between n-nitrosomethylurea and potassium hydroxide in n-butyl ether resulted in an explosion due to the formation of diazomethane [Schwab 1972]. Potassium persulfate and a little potassium hydroxide and water ignited a polythene (polyethylene) liner of a container by release of heat and oxygen [MCA Case History 1155.
  CAMEO Chemicals
• Forms crusts on exposure to air (from absorption of carbon dioxide). Water soluble. Dilution of concentrated solutions generates heat.
  CAMEO Chemicals

Incompatible materials and hazardous reactions

• Acids, water, metals (when wet), halogenated hydrocarbons, maleic anhydride [Note: Heat is generated if KOH comes in contact with water & carbon dioxide from the air].
  Hazardous Substances Data Bank (HSDB)
• Above 84 °C it reacts with reducing sugars to form poisonous carbon monoxide gas. Violent, exothermic reaction with water. Potentially explosive reaction with bromoform + crown ethers, chlorine dioxide, nitrobenzene, nitromethane, nitrogen trichloride, peroxidized tetrahydrofuran, 2,4,6-trinitrotoluene. Reaction with ammonium hexachloroplatinate(2-) + heat forms a heat-sensitive explosive product. Violent reaction or ignition under the appropriate conditions with acids, alcohols, p-bis(1,3-dibromoethyl)benzene, cyclopentadiene, germanium, hyponitrous acid, maleic anhydride, nitroalkanes, 2-nitrophenol, potassium peroxodisulfate, sugars, 2,2,3,3-tetrafluoropropanol, thorium dicarbide.
  Hazardous Substances Data Bank (HSDB)
• Molten ortho nitrophenol reacts violently with potassium hydroxide (commercial 85% pellets). When solid potassium hydroxide & tetrachloroethane are heated, a spontaneously flammable gas, chloroacetylene, is formed.
  Hazardous Substances Data Bank (HSDB)

11Toxicological information

Target organs

• Eyes, skin, respiratory system
  The National Institute for Occupational Safety and Health (NIOSH)

Short-term exposure effects

• The substance is very corrosive to the eyes, skin and respiratory tract. Corrosive on ingestion.
  ILO-WHO International Chemical Safety Cards (ICSCs)

Long-term exposure effects

• Repeated or prolonged contact with skin may cause dermatitis.
  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

• SRP: Recycle any unused portion of the material for its approved use or return it to the manufacturer or supplier. Ultimate disposal of the chemical must consider: the material's impact on air quality; potential migration in air, soil or water; effects on animal, aquatic and plant life; and conformance with environmental and public health regulations. If it is possible or reasonable use an alternative chemical product with less inherent propensity for occupational harm/injury/toxicity or environmental contamination.
  Hazardous Substances Data Bank (HSDB)
• Neutralization & discharge to sewer: Carefully dissolve in water and neutralize with dilute acetic acid. Flush to sewer with lots of water, regulations permitting or dispose of through a licensed contractor. Consider use of waste caustic for neutralizing plant acid wastes.
  Hazardous Substances Data Bank (HSDB)

14Transport information

UN numbers: UN 1813, UN 1814, UN 3171

Shipping name

• UN 1813; Potassium hydroxide, solid
  Hazardous Substances Data Bank (HSDB)
• UN 1814; Potassium hydroxide. solution
  Hazardous Substances Data Bank (HSDB)

DOT hazard class

• Potassium hydroxide, solid
  US Code of Federal Regulations, Hazardous Materials, 49 CFR Part 172
• UN1813
  US Code of Federal Regulations, Hazardous Materials, 49 CFR Part 172
• Class 8 Corrosive material (49 eCFR § 173.136)
  US Code of Federal Regulations, Hazardous Materials, 49 CFR Part 172

DOT label

• Corrosive
  CAMEO Chemicals

UN classification

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

Emergency Response Guidebook

• 1813 154
  Emergency Response Guidebook (ERG)
• 1814 154
  Emergency Response Guidebook (ERG)

How DOT hazard classes work →

15Regulatory information

• Residues of potassium hydroxide are exempted from the requirement of a tolerance when used in accordance with good agricultural practice as inert (or occasionally active) ingredients in pesticide formulations applied to growing crops or to raw agricultural commodities after harvest. Use: neutralizer.
  Hazardous Substances Data Bank (HSDB)
• As the federal pesticide law FIFRA directs, EPA is conducting a comprehensive review of older pesticides to consider their health and environmental effects and make decisions about their continued use. Under this pesticide reregistration program, EPA examines newer health and safety data for pesticide active ingredients initially registered before November 1, 1984, and determines whether the use of the pesticide does not pose unreasonable risk in accordance to newer safety standards, such as those described in the Food Quality Protection Act of 1996.
  Hazardous Substances Data Bank (HSDB)
• Potassium hydroxide is designated as a hazardous substance under section 311(b)(2)(A) of the Federal Water Pollution Control Act and further regulated by the Clean Water Act Amendments of 1977 and 1978. These regulations apply to discharges of this substance. This designation includes any isomers and hydrates, as well as any solutions and mixtures containing this substance.
  Hazardous Substances Data Bank (HSDB)
• Persons in charge of vessels or facilities are required to notify the National Response Center (NRC) immediately, when there is a release of this designated hazardous substance, in an amount equal to or greater than its reportable quantity of 1000 lb or 454 kg. The toll free number of the NRC is (800) 424-8802. The rule for determining when notification is required is stated in 40 CFR 302.4 (section IV. D.3.b).
  Hazardous Substances Data Bank (HSDB)
• Substance added directly to human food affirmed as generally recognized as safe (GRAS).
  Hazardous Substances Data Bank (HSDB)

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

16Other information

Compiled from PubChem CID 14797 and the sources it aggregates (attributed inline). Data retrieved 2026-10-12. This summary describes the pure substance and is not a supplier SDS.