Thioisonicotinamide is primarily used in organic synthesis and pharmaceutical research due to its sulfur- and nitrogen-containing heterocyclic structure. It serves as a key intermediate in the preparation of various biologically active compounds, including potential antimicrobial and antitumor agents. Its thioamide functional group allows for coordination with metal ions, making it useful in the development of metal complexes with catalytic or medicinal properties. Additionally, it has been investigated as a building block in the synthesis of thiazole and thiadiazole derivatives, which are important scaffolds in drug design. The compound also finds application in the study of enzyme inhibition, particularly in reactions involving pyridine metabolism analogs.