Ammonium oxalate is a chemical compound with the chemical formula 2O4. Its formula is often written as 24). The structure of ammonium oxalate is ([NH4]+)2[C2O4]2. Ammonium oxalate sometimes comes as a monohydrate ([NH4]2C2O4·H2O). It is a colorless or white salt under standard conditions and is odorless and non-volatile. It occurs in many plants and vegetables.