Sodium hydroxide (
NaOH), also known as
lye and
caustic soda, is an
inorganic compound. It is a white solid and highly
caustic metallic
base and
alkali salt of
sodium which is available in pellets, flakes, granules, and as prepared solutions at a number of different concentrations. Sodium hydroxide forms an approximately 50% (by weight)
saturated solution with water.