Tetramethyl­ammonium fluoride, commonly abbreviated TMAF, is the quaternary ammonium salt with the formula (CH3)4NF.

This hygroscopic white solid is a source of “naked fluoride": fluoride ions not complexed with a metal atom.

Most other soluble salts of fluoride are in fact bifluorides, HF2–.

Historically, there have been two main approaches to prepare tetramethyl­ammonium fluoride: hydrofluoric acid neutralization of tetramethyl­ammonium hydroxide, and salt metathesis between different ammonium salts and inorganic fluoride sources, such as KF or CsF.

[1] Because the fluoride anion is extremely basic, the salt slowly reacts with acetonitrile, inducing dimerization to CH3C(NH2)=CHCN, which co-crystallizes.