Hydrazine hydrate (HH) is a colorless, oily, fuming liquid with an ammonia-like odor. It has many applications, including as an intermediate for pharmaceuticals, plasticizers, rubber chemicals, and pesticides. It is also used as a reducing agent, corrosion inhibitor, and oxygen scavenger.

In pharmaceuticals, HH is used as a source for the drug hydralazine, an anti-tubercular drug. It is also used as a reagent in the synthesis of 3-amino-2-thiohydantoins.

HH is toxic if swallowed, in contact with skin, or inhaled. It can cause severe skin burns, eye damage, and allergic skin reactions. It is also very toxic to aquatic life. When handling HH, you should wear protective gloves, clothing, eye protection, and face protection. If swallowed, you should rinse your mouth but do not induce vomiting. If it gets on your skin, you should gently wash it off.