Thioamides are typically prepared by treating amides with phosphorus sulfides such as phosphorus pentasulfide, a reaction first described in the 1870s. Alternative routes include the use of Lawesson's reagent or the reaction of nitriles with hydrogen sulfide:
The Willgerodt-Kindler reaction also gives benzylthioamides.
The C(R)(N)(S) core of thioamides is planar. Using thioacetamide as representative: the C-S, C-N, and C-C distances are 1.68, 1.31, and 1.50 Å, respectively. The short C-S and C-N distances indicate multiple bonding.