2-Thiobenzimidazole (2-TBI), also known as 2-mercaptobenzimidazole, is a chemical compound with the formula C7H6N2S that exists in both a thione (c=s) and a thiol (c-sh) form, which can tautomerize between each other. It is a versatile molecule used as a ligand in coordination chemistry, an antioxidant, an intermediate in the synthesis of pharmaceuticals and other chemicals, and has shown significant biological activities including antifungal, anti-inflammatory, and antitumor properties. It is also a component in the rubber industry.