Antimony trisulfide is a gray solid. It reacts with hydrochloric acid to make hydrogen sulfide and an antimony(III) compound. It dissolves in potassium hydroxide. It burns in air to make antimony(III) oxide and sulfur dioxide. It is a reducing agent.
Antimony trisulfide is made in the laboratory by reacting any antimony(III) compound with hydrogen sulfide.
Antimony trisulfide is used in cosmetics; in this area it is called kohl. It is used in pyrotechnics to make a glitter effect. It is also used in the heads of safety matches. It used to be used in flash powder before electronic flashes were used.