Liquid oxygen has a pale blue color and is strongly paramagnetic: it can be suspended between the poles of a powerful horseshoe magnet. Liquid oxygen has a density of 1.141 g/cm3 (1.141 kg/L or 1141 kg/m3), slightly denser than liquid water, and is cryogenic with a freezing point of 54.36 K (?218.79 °C; ?361.82 °F) and a boiling point of 90.19 K (?182.96 °C; ?297.33 °F) at 101.325 kPa (760 mmHg). Liquid oxygen has an expansion ratio of 1:861 under 1 standard atmosphere (100 kPa) and 20 °C (68 °F), and because of this, it is used in some commercial and military aircraft as a transportable source of breathing oxygen.
Because of its cryogenic nature, liquid oxygen can cause the materials it touches to become extremely brittle. Liquid oxygen is also a very powerful oxidizing agent: organic materials will burn rapidly and energetically in liquid oxygen. Further, if soaked in liquid oxygen, some materials such as coal briquettes, carbon black, etc., can detonate unpredictably from sources of ignition such as flames, sparks or impact from light blows. Petrochemicals, including asphalt, often exhibit this behavior.