In thiols, the sulfur atom is an unequal sp hybrid state, the sp hybridization orbitals occupied by two single electrons form a σ bond with the hydrocarbyl carbon and hydrogen, respectively, and two pairs of lone pairs occupy another two sp hybrids. track. Since the hybrid orbitals formed by the 3s and 3p orbitals of sulfur are larger than the hybrid orbitals formed by the 2s and 2p orbitals of oxygen, the C-S and S-H bonds are longer than the C-O and O-H bonds, respectively.

The C-S and S-H bond lengths in the methyl mercaptan were 0.182 nm and 0.134 nm, respectively, both of which were longer than the C-O and O-H bonds in methanol. ∠CSH is 96°, less than ∠COH.

Sulfur has a lower electronegativity than oxygen, so the thiol dipole moment is also smaller than the corresponding alcohol.