Diethyl Oxalate, also known as ethyl ester, is Oily, colorless & clear liquid with the molecular formula C₆H₁₀O₄. The DEO works as an intermediate, mostly decomposes in water very slowly but proving insoluble in the same. However it mixes well together with Acetone & Alcohol, undergoes typical ester reactions, including condensation and transesterification.

Diethyl Oxalate typically being used in Pharmaceuticals manufactures to forms the block for different drugs. It is also used in producing dyes & other plastic intermediates along with the application in solvents.