Malonyl chloride is the organic compound with the formula CH2(COCl)2.

It is the acyl chloride derivative of malonic acid.

It is a colorless liquid although samples are often deeply colored owing to impurities.

The compound degrades at room temperature after a few days.

Heating in the presence of non-nucleophilic base gives the ketene derivative O=C=C(H)COCl.