Flammability and Explosibility


Reactivity and Incompatibility

Osmium tetroxide reacts with hydrochloric acid to form chlorine gas.

Storage and Handling

Because of its high acute toxicity, osmium tetroxide should be handled in the laboratory using the "basic prudent practices" of Chapter 5.C, supplemented by the additional precautions for work with compounds of high toxicity (Chapter 5.D). In particular, all work with osmium tetroxide should be conducted in a fume hood to prevent exposure by inhalation, and splash goggles and impermeable gloves should be worn at all times to prevent eye and skin contact. Osmium tetroxide as solid or solutions should be stored in tightly sealed containers, and these should be placed in secondary containers.


In the event of skin contact, immediately wash with soap and water and remove contaminated clothing. In case of eye contact, promptly wash with copious amounts of water for 15 minutes (lifting upper and lower lids occasionally) and obtain medical attention. If osmium tetroxide is ingested, obtain medical attention immediately. If large amounts are inhaled, move the person to fresh air and seek medical attention at once.

In the event of a spill, mix osmium tetroxide with an absorbent material such as vermiculite or dry sand (avoid raising dust), place in an appropriate container, and dispose of properly. Evacuation and cleanup using respiratory protection may be necessary in the event of a large spill or release in a confined area.


Excess osmium tetroxide solutions can be rendered safer by reaction with sodium sulfite to produce insoluble osmium dioxide. Ethanol will also react to produce the dioxide. Corn oil or sodium sulfide may also be used to deactivate osmium tetroxide. Osmium containing waste should be placed in a tightly sealed, labeled container and handled according to your institution's waste disposal guidelines. For more information on disposal procedures, see Chapter 7 of this volume.

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