Hydrazine or hydrazine hydrate is an inorganic chemical compound with the formula N2H4. It is a colourless flammable liquid with an ammonia-like odor and is derived from the same industrial chemistry processes that manufacture ammonia. However, Hydrazine has physical properties that are closer to those of water.

Hydrazine is highly toxic and dangerously unstable, and is usually handled while in solution for safety reasons.

Hydrazine is mainly used as a foaming agent in preparing polymer foams, but significant applications also include its uses as a precursor to polymerization catalysts and pharmaceuticals. Additionally, Hydrazine is used in various rocket fuels and to prepare the gas precursors used in air bags.

It is used within both nuclear and conventional electrical power plant steam cycles to control concentrations of dissolved oxygen in an effort to reduce corrosion.

It is used within electrical power plant steam cycles to control concentrations of dissolved oxygen in an effort to reduce corrosion.

Hydrazine is also used within electrical power plant steam cycles to control concentrations of dissolved oxygen in an effort to reduce corrosion.

For safety issues, Hydrazine is highly toxic and dangerously unstable, especially in the anhydrous form. Symptoms of acute (short-term) exposure to high levels of Hydrazine may include irritation of the eyes, nose, and throat, dizziness, headache, nausea, pulmonary edema, seizures, coma in humans. Acute exposure can also damage the liver, kidneys, and central nervous system. The liquid is corrosive and may produce dermatitis from skin contact in humans and animals. Effects to the lungs, liver, spleen, and thyroid have been reported in animals chronically exposed to hydrazine via inhalation. Increased incidences of lung, nasal cavity, and liver tumors have been observed in rodents exposed to Hydrazine.