Three new sulfated alkenes (1-3), trimethylammonium (5R)-5,9-dimethyl-(3E)-3,8-decadienyl-1-sulfate, dimethylammonium (5R)-5,9-dimethyl-(3E)-3,8-decadienyl-1-sulfate, and 2'-methyl-4'-oxobutan-2-ylammonium (5R)-5,9-dimethyl-(3E)-3,8-decadienyl-1-sulfate, were isolated from an echinoderm, Temnopleurus hardwickii. Their structures were elucidated by spectral analysis and chemical degradation methods.