Melting point :315 °C (subl.)(lit.)
Boiling point :684.9 °C(lit.)
Density :4.81 g/mL at 25 °C(lit.)
vapor pressure :1 mm Hg ( 157 °C)
refractive index :nD20 <1.76
Flash point :315°C
storage temp. :Store below +30°C.
solubility :H₂O: soluble
form :powder
color :white
Specific Gravity :3.95
PH :2 (10g/l, H2O, 20℃)
Water Solubility :38.4 g/100 mL (14 ºC)
Sublimation :315 ºC
Merck :14,8434
crystal system :square
Space group :P42/mbc
Lattice constant :

a/nm	b/nm	c/nm	α/o	β/o	γ/o	V/nm3
0.83622	0.83622	0.50612	90	90	90	0.3539

Exposure limits :ACGIH: TWA 0.2 mg/m3
NIOSH: IDLH 1 mg/m3; TWA 0.2 mg/m3 Stability :Stable. Incompatible with organic materials, strong acids, ammonia, nitric acid, halogen acids. Protect from moisture.
InChI :1S/O2Se/c1-3-2
InChIKey :JPJALAQPGMAKDF-UHFFFAOYSA-N
SMILES :O=[Se]=O
CAS DataBase Reference :7446-08-4(CAS DataBase Reference)
NIST Chemistry Reference :Selenium dioxide(7446-08-4)
EPA Substance Registry System :Selenium dioxide (7446-08-4)

Symbol(GHS):
Signal word:	Danger
Hazard statements:	Code Hazard statements Hazard class Category Signal word Pictogram P-Codes H300 Fatal if swallowed Acute toxicity,oral Category 1, 2 Danger P264, P270, P301+P310, P321, P330,P405, P501 H319 Causes serious eye irritation Serious eye damage/eye irritation Category 2A Warning P264, P280, P305+P351+P338,P337+P313P H331 Toxic if inhaled Acute toxicity,inhalation Category 3 Danger P261, P271, P304+P340, P311, P321,P403+P233, P405, P501 H370 Causes damage to organs Specific target organ toxicity, single exposure Category 1 Danger P260, P264, P270, P307+P311, P321,P405, P501 H372 Causes damage to organs through prolonged or repeated exposure Specific target organ toxicity, repeated exposure Category 1 Danger P260, P264, P270, P314, P501 H410 Very toxic to aquatic life with long lasting effects Hazardous to the aquatic environment, long-term hazard Category 1 Warning P273, P391, P501
Precautionary statements:	P260 Do not breathe dust/fume/gas/mist/vapours/spray. P264 Wash hands thoroughly after handling. P264 Wash skin thouroughly after handling. P270 Do not eat, drink or smoke when using this product. P271 Use only outdoors or in a well-ventilated area. P273 Avoid release to the environment. P280 Wear protective gloves/protective clothing/eye protection/face protection. P305+P351+P338 IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continuerinsing. P337+P313 IF eye irritation persists: Get medical advice/attention. P391 Collect spillage. Hazardous to the aquatic environment P403+P233 Store in a well-ventilated place. Keep container tightly closed. P405 Store locked up. P501 Dispose of contents/container to..…