Thioisonicotinamide is primarily used in organic synthesis and medicinal chemistry due to its sulfur- and nitrogen-containing heterocyclic structure. It serves as a key intermediate in the preparation of various biologically active compounds, particularly in the development of antimicrobial and antitubercular agents. Its thioamide functionality allows it to act as a ligand in coordination chemistry, forming complexes with metal ions that can be explored for catalytic or pharmacological applications. Additionally, it has been investigated for its potential in synthesizing heterocyclic scaffolds used in drug discovery, especially for targeting enzyme inhibition. Its reactivity also makes it useful in the construction of thiazole and thiadiazole derivatives, which are common motifs in pharmaceuticals.