12-Crown-4, also called 1,4,7,10-tetraoxacyclododecane and lithium ionophore V, is a crown ether with the formula C8H16O4.

It is a cyclic tetramer of ethylene oxide which is specific for the lithium cation.

12-Crown-4 can be synthesized using a modified Williamson ether synthesis, using LiClO4 as a templating cation:[1] It also forms from the cyclic oligomerization of ethylene oxide in the presence of gaseous boron trifluoride.

[2] Like other crown ethers, 12-crown-4 complexes with alkali metal cations.

The cavity diameter of 1.2-1.5 Å gives it a high selectivity towards the lithium cation (ionic diameter 1.36 Å)[2] Its point group is S4.