Octadecene is a long-chain hydrocarbon and an alkene with the molecular formula C18H36. There are multiple structural isomers of octadecene, depending on the position of the double bond. 1-Octadecene, an alpha-olefin, is a relatively inexpensive solvent, with a boiling point of 315 °C. It is compatible with oleic acid.
Octadecene is used in the synthesis of colloidal quantum dots, but it can possibly be replaced by heat transfer fluids such as Dowtherm A or Therminol 66 in this process.