2-[4-(2-Hydroxyethyl)piperazin-1-yl]ethanesulfonic acid

The title compound, C8H18N2O4S, is a useful buffer in the physiological pH range. In the crystal structure, the piperazine ring adopts a chair conformation. One weak intramolecular C—H⋯O hydrogen bond, together with one weak intermolecular C—H⋯O and two strong intermolecular O—H⋯N hydrogen bonds are present, the latter linking the mol­ecules into a reticulation framework.