Sodium sulfide, an inorganic compound also also known as odorous alkali, odorous soda, yellow alkali, or sulfide alkali, is a colorless crystalline powder in its pure form. It is highly hygroscopic and readily soluble in water, yielding an aqueous solution that exhibits strongly alkaline properties. Contact with skin or hair can cause burns, hence its common name “sulfide alkali.” When exposed to air, the aqueous solution of sodium sulfide gradually oxidizes to form sodium thiosulfate, sodium sulfite, sodium sulfate, and sodium polysulfide. Among these, sodium thiosulfate is generated at a relatively faster rate, making it the primary oxidation product. Sodium sulfide is also prone to deliquescence and carbonation in air, leading to decomposition and the continuous release of hydrogen sulfide gas. Industrial-grade sodium sulfide often contains impurities, imparting shades such as pink, reddish-brown, or yellowish-brown. The specific gravity, melting point, and boiling point of the compound may vary due to the influence of these impurities.

Sodium sulfide has SGS third-party certification, industrial grade certification, and has passed ISO international quality system certification and REACH compliance certification.