Malonic anhydride or oxetane-2,4-dione is an organic compound with chemical formula C3H2O3 or CH2(CO)2O.

It can be viewed as the anhydride of malonic acid, or a double ketone of oxetane.

Malonic anhydride was first synthesized in 1988 by ozonolysis of diketene.

[1][2] Some derivatives, such as 3,3-dimethyl-oxetane-2,4-dione, are known.

[3][4][5]