Osmium tetroxide

254.20 g·mol−1

1.04 g/cm3

40 °C

130 °C

-40 °C

Soluble in water (72 mg/ml), alcohol, ether, and chloroform (3750 mg/ml).

colorless or yellow solid

UN 3175 4.1/PG 2

R11 - Highly flammable
R19 - May form explosive peroxides
R23/24/25 - Toxic by inhalation, in contact with skin and if swallowed
R26/27/28 - Very toxic by inhalation, in contact with skin and if swallowed
R34 - Causes burns
R36/37/38 - Irritating to eyes, respiratory system and skin
R40 - Limited evidence of a carcinogenic effect
R42/43 - May cause sensitization by inhalation and skin contact
R66 - Repeated exposure may cause skin dryness or cracking
R67 - Vapours may cause drowsiness and dizziness
R8 - Contact with combustible material may cause fire

S16 - Keep away from sources of ignition - No smoking
S17 - Keep away from combustible material
S23 - Do not breathe gas/fumes/vapour/spray (appropriate wording to be specified by the manufacturer)
S26 - In case of contact with eyes, rinse immediately with plenty of water and seek medical advice
S27 - Take off immediately all contaminated clothing
S28 - After contact with skin, wash immediately with plenty of ... (to be specified by the manufacturer)
S36/37 - Wear suitable protective clothing and gloves
S36/37/39 - Wear suitable protective clothing, gloves and eye/face protection
S45 - In case of accident or if you feel unwell seek medical advice immediately (show the label where possible)
S7/9 - Keep container tightly closed and in a well-ventilated place

O, T, C, T+, Xi, Xn, F