(2-Hydroxyethyl) dimethylsulfoxonium chloride is an organic compound with the formula . This sulfonium salt has been isolated from sea chervils (genus Alcyonidium) and a single species of sea sponge. It can cause a disease known as Dogger Bank itch.
(2-Hydroxyethyl) dimethylsulfoxonium chloride is a colourless to white powder that dissolves in 1,4-dioxane, methanol, chloroform or water.
(2-Hydroxyethyl) dimethylsulfoxonium chloride is a salt, with a sulfur atom having a positive charge. Attached to the sulfur are two methyl groups, a double bonded oxygen atom, and an ethanol tail group attached at the number 2 carbon. The structure of this toxin has been confirmed by X-ray crystallography.