Calcium oxide

E number E529INS 529CAS 1305-78-8

Used as an acidity regulator — Codex also lists it as flour, treatment agent.

Calcium oxide, or quicklime, is an alkaline acidity regulator and processing aid used in sugar refining, maize processing and dairy.

Where it is and isn’t permitted

Status of Calcium oxide by jurisdiction. Every jurisdiction this site covers is listed, including those where the substance does not appear.
JurisdictionStatusScope and limitsCitation
United StatesFood and Drug AdministrationPermitted21 CFR 184.1210retrieved 2026-09-07
Codex AlimentariusCodex Alimentarius Commission / JECFAPermitted, with conditions

1 food category

no numerical limit (good manufacturing practice)

CXS 192-1995 Table Three, INS 529and 1 further provisionretrieved 2026-09-07

What it is made from

Produced by heating limestone to drive off carbon dioxide. It reacts vigorously with water to form calcium hydroxide.

  • Vegan
  • Vegetarian
CAS registry number
1305-78-8
InChIKey
ODINCKMPIJJUCX-UHFFFAOYSA-N
PubChem
CID 14778

Every name it appears under

66 recorded names. A label may use any of them.

E number

  • E529

INS number

  • 529

CAS registry number

  • 1305-78-8

As it appears in regulation

  • Calcium oxide

Other names

  • Aetzkalk
  • Airlock
  • BDFERM BIOSPRAY
  • Bell CML(E)
  • Bell CML(P)
  • Branntkalk
  • Burned lime
  • Burnt lime
  • C7X2M0VVNH
  • Calcia
  • Calcia (CaO)
  • Calcium monoxide
  • Calcium oxide
  • Calcium oxide (CaO)
  • Calcium oxide (JP17)
  • Calcium oxide, 99.995% trace metals basis
  • Calcium oxide, CP
  • Calcium oxide, p.a., 95.0%
  • Calcium oxide, SAJ first grade, >=98.0%
  • Calcium oxide, SAJ special grade, >=98.0%
  • Calcium oxide, Vetec(TM) reagent grade
  • Caloxal CPA
  • Caloxol CP2
  • CALOXOL W 3
  • Caloxol W3
  • CALX
  • Calx usta
  • Calxyl
  • Caswell No. 147A
  • CCRIS 7496
  • Chaux vive
  • CML 21
  • CML 31
  • CML 35
  • Desical P
  • E 529
  • EPA Pesticide Chemical Code 075604
  • EVECODE ECO FRIENDLY MULTI SANITIZERspray
  • EVECODE Eco-Friendly Safe SanitizerSpray
  • Gebrannter kalk
  • heavy calcium oxide
  • HSDB 1615
  • INS NO.529
  • INS-529
  • Kalziumoxid
  • Lime (Calcium Oxide)
  • Lime (cao)
  • Lime (USP)
  • Lime [USP]
  • Lime, burned
  • Lime, meets USP testing specifications
  • oxocalcium
  • Oxyde de calcium
  • Pebble lime
  • Quick lime
  • Quicklime
  • Rhenosorb C
  • Rhenosorb F
  • Unslaked lime
  • Vesta PP
  • Wapniowy tlenek

Systematic names

  • calcium oxide

Hazard reference values

No reference value for this substance in the sources we hold.

Evidence and how bodies read it

Studies, and the differing conclusions regulators drew from them, are curated by hand rather than machine-read, and none has been written for this substance yet.

Sources for this page

  • ecfr retrieved 2026-09-07
  • gsfa retrieved 2026-09-07

Full licence terms and publisher details on Sources. How this page is built and updated: Method.

Machine-readable:/api/v1/additives/calcium-oxide.json