4-Methylbenzenethiol (p-Toluenethiol) is an organosulfur compound consisting of a benzene ring substituted with a thiol (-SH) group and a methyl (-CH₃) group at the para position. It is commonly used as an intermediate in organic synthesis, polymer chemistry, and as a chemical modifier in materials science. The thiol group makes it reactive in thiolation and coupling reactions, while the methyl group influences its solubility and reactivity.