(GOX, gas only; LOX, liquid only)

CAS 7782-44-7



Physical Properties

Colorless gas

bp -183 °C, mp -219 °C

Slightly soluble in water (0.004 g/100 mL at 25°C)


Odorless gas

Vapor Density

1.11 (air = 1.0)

Vapor Pressure

>760 mmHg at 20 °C

Toxicity Data

OSHA recommends a minimum oxygen concentration of 19.5% for human occupancy.

Major Hazards

Powerful oxidizing agent; concentrations greater than 25% greatly enhance the combustion rate of many materials.


Oxygen is nontoxic under the usual conditions of laboratory use. Breathing pure oxygen at one atmosphere may produce cough and chest pains within 8 to 24 h, and concentrations of 60% may produce these symptoms in several days. Liquid oxygen can cause severe "burns" and tissue damage on contact with the skin due to extreme cold.

Flammability and Explosibility

Oxygen itself is nonflammable, but at concentrations greater than 25% supports and vigorously accelerates the combustion of flammable materials. Some materials (including metals) that are noncombustible in air will burn in the presence of oxygen.

Reactivity and Incompatibility

Oxygen is incompatible with combustible materials, including many lubricants and elastomers. Oil, greases, and other readily combustible substances should never be allowed to come in contact with O2 cylinders, valves, regulators, and fittings. Contact of liquid oxygen with many organic substances can lead to an explosion.

Storage and Handling

Oxygen should be handled in the laboratory using the "basic prudent practices" described in Chapter 5.C, supplemented by the procedures for work with compressed gases found in Chapter 5.H.


In the event of skin or eye contact with liquid oxygen, seek medical attention for cryogenic burns. Do not enter areas of high oxygen gas concentration, which can saturate clothing and increase its flammability. Ventilate area to evaporate and disperse oxygen.

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