硫醇是包含巯基官能团（-SH）的一类非芳香化合物。是一类有机硫化合物。可以看成醇中的氧被硫替换

硫醇中，硫原子为不等性sp杂化态，两个单电子占据的sp杂化轨道分别与烃基碳和氢形成σ键，还有两对孤对电子占据另外的两个sp杂化轨道。由于硫的3s和3p轨道形成的杂化轨道比氧的2s和2p轨道形成的杂化轨道大，故C-S和S-H键分别比C-O和O-H键长。在甲硫醇中C-S和S-H键键长分别为0.182 nm和0.134 nm，都比甲醇中的C-O和O-H键长大。∠CSH则为96°，小于∠COH。

硫的电负性比氧小，所以硫醇的偶极矩也比相应的醇小。

In organic chemistry, a thiol (/ˈθaɪɔːl/, /ˈθaɪɒl/) is an organosulfur compound that contains a carbon-bonded sulfhydryl or sulphydryl (–C–SH or R–SH) group (where R represents an alkyl or other organic substituent). Thiols are the sulfur analogue of alcohols (that is, sulfur takes the place of oxygen in the hydroxyl group of an alcohol), and the word is a portmanteau of "thion" + "alcohol," with the first word deriving from Greek θεῖον (theion) = "sulfur". The –SH functional group itself is referred to as either a thiol group or a sulfhydryl group.