# NIOSH Pocket Guide to Chemical Hazards
Cesium hydroxide | CAS 21351-79-1
CsOH | RTECS FK9800000
Synonyms & Trade Names Cesium hydrate, Cesium hydroxide dimer | DOT ID & Guide 2682 157 2681 154 (solution)
Exposure Limits | NIOSH REL: TWA 2 mg/m3
OSHA PEL†: none
IDLH N.D. | Conversion
Physical Description Colorless or yellowish, crystalline solid. [Note: Hygroscopic (i.e., absorbs moisture from the air).]
MW: 149.9 | BP: ? | MLT: 522°F | Sol(59°F): 395%
VP: 0 mmHg (approx) | IP: NA |  | Sp.Gr: 3.68
Fl.P: NA | UEL: NA | LEL: NA |
Noncombustible Solid
Incompatibilities & Reactivities Water, acids, CO2, metals (e.g., Al, Pb, Sn, Zn), oxygen [Note: CsOH is a strong base, causing the generation of considerable heat in contact with water or moisture.]
Measurement Methods None available
Personal Protection & Sanitation Skin: Prevent skin contact Eyes: Prevent eye contact Wash skin: When contaminated Remove: When wet or contaminated Change: Daily Provide: Eyewash, Quick drench | First Aid (See procedures) Eye: Irrigate immediately Skin: Water flush immediately Breathing: Respiratory support Swallow: Medical attention immediately
Respirator Recommendations To be added later
Exposure Routes inhalation, ingestion, skin and/or eye contact
Symptoms Irritation eyes, skin, upper respiratory system; eye, skin burns
Target Organs Eyes, skin, respiratory system
See also: INTRODUCTION