Methylethyl ketone oxime is the organic compound with the formula C2H5C(NOH)CH3.

This colourless liquid is the oxime derivative of methyl ethyl ketone.

MEKO functions by binding the drying agents, metal salts that catalyze the oxidative crosslinking of drying oils.

Once the paint is applied to a surface, MEKO evaporates, thereby allowing the drying process to proceed.

Other antiskinning agents have been used, including phenolic antioxidants (E.G butylated hydroxytoluene), but these tend to yellow the paint.