Melting point :172-175 °C(lit.)
Boiling point :285 °C(lit.)
Density :1.32
vapor density :3.81 (vs air)
vapor pressure :1 mm Hg ( 132 °C)
refractive index :1.6320
Flash point :165 °C
storage temp. :Store below +30°C.
solubility :H₂O: 50 mg/mL, clear
pka :10.35(at 20℃)
form :Needle-Like Crystals or Crystalline Powder
color :White to off-white
Odor :odorless
Water Solubility :70 g/L (20 ºC)
Sensitive :Air & Light Sensitive
Merck :14,4808
BRN :605970
Henry's Law Constant :(x 10^-9 atm?m³/mol): <2.07 at 20 °C (approximate - calculated from water solubility and vapor pressure)
Exposure limits :NIOSH REL: 15-min ceiling 2, IDLH 50; OSHA PEL: TWA 2; ACGIH TLV: TWA 2 (adopted).
Stability :Stable. Combustible. Incompatible with strong oxidizing agents, strong bases, oxygen, ferric salts. Light and air-sensitive. Discolours in air.
InChIKey :QIGBRXMKCJKVMJ-UHFFFAOYSA-N
LogP :0.59 at 20℃
CAS DataBase Reference :123-31-9(CAS DataBase Reference)
IARC :3 (Vol. 15, Sup 7, 71) 1999
NIST Chemistry Reference :Hydroquinone(123-31-9)
EPA Substance Registry System :Hydroquinone (123-31-9)

Symbol(GHS):
Signal word:	Danger
Hazard statements:	Code Hazard statements Hazard class Category Signal word Pictogram P-Codes H302 Harmful if swallowed Acute toxicity,oral Category 4 Warning P264, P270, P301+P312, P330, P501 H318 Causes serious eye damage Serious eye damage/eye irritation Category 1 Danger P280, P305+P351+P338, P310 H341 Suspected of causing genetic defects Germ cell mutagenicity Category 2 Warning P201,P202, P281, P308+P313, P405,P501 H351 Suspected of causing cancer Carcinogenicity Category 2 Warning P201, P202, P281, P308+P313, P405,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:	P202 Do not handle until all safety precautions have been read and understood. P273 Avoid release to the environment. P280 Wear protective gloves/protective clothing/eye protection/face protection. P301+P312 IF SWALLOWED: call a POISON CENTER or doctor/physician IF you feel unwell. P305+P351+P338 IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continuerinsing. P308+P313 IF exposed or concerned: Get medical advice/attention.