Mercapto Group Definition

This is the chemical structure of cysteine.
This is the chemical structure of cysteine. The yellow SH on the left hand side is a mercapto group. Todd Helmenstine

Definition: A mercapto group is a fuctional group containing a sulfur atom bonded to a hydrogen atom. General formula: -SH

Also Known As: thiol group, sulfanyl group

Examples: The amino acid cysteine contains a mercapto group.