<p><strong>Definition: </strong>A thiol group is a <a href="https://www.thoughtco.com/definition-of-functional-groups-604473" data-component="link" data-source="inlineLink" data-type="internalLink" data-ordinal="1">fuctional group</a> containing a <a href="https://www.thoughtco.com/sulfur-facts-606599" data-component="link" data-source="inlineLink" data-type="internalLink" data-ordinal="2">sulfur</a> <a href="https://www.thoughtco.com/definition-of-atom-and-examples-604373" data-component="link" data-source="inlineLink" data-type="internalLink" data-ordinal="3">atom</a> bonded to a <a href="https://www.thoughtco.com/hydrogen-facts-606544" data-component="link" data-source="inlineLink" data-type="internalLink" data-ordinal="4">hydrogen</a> atom. General formula: -SH</p><p><strong>Also Known As: </strong>sulfanyl group, mercapto group</p><p><strong>Examples: </strong>The amino acid cysteine contains a thiol group.</p>