Diacetyl monoxime is a chemical compound described by the formula CH3C(O)C(NOH)CH3.

This colourless solid is the monooxime derivative of the diketone butane-2,3-dione (also known as diacetyl and biacetyl).

Its biological effects include inhibiting certain ATPases.

[1] The compound can be prepared from butanone by reaction with ethyl nitrite.

It is an intermediate in the preparation of dimethylglyoxime:[2] Diacetyl monoxime can be used with thiosemicarbazide to selectively detect small amounts of urea in the presence of other nitrogen-containing compounds.