硫醛（R-CSH）是一类有机化合物的通称，可以看作醛中的氧（O）原子被硫（S）原子取代。

• 硫代丙醛
• 二硫代氨基甲酸二乙胺盐
• 噻啶
• 硫烯比妥

A thial or thioaldehyde is a functional group in organic chemistry which is similar to an aldehyde, RC(O)H, in which a sulfur (S) atom replaces the oxygen (O) atom of the aldehyde (R represents an alkyl or aryl group). Thioaldehydes are even more reactive than thioketones. Unhindered thioaldehydes are generally too reactive to be isolated — for example, thioformaldehyde, H₂C=S, condenses to the cyclic trimer 1,3,5-trithiane. Thioacrolein, H₂C=CHCH=S, formed by decomposition of allicin from garlic, undergoes a self Diels-Alder reaction giving isomeric vinyldithiins. While thioformaldehyde is highly reactive, it is thermodynamically quite stable and is found in interstellar space along with its mono- and di-deuterated isotopologues. With sufficient steric bulk, however, stable thioaldehydes can be isolated.