Diammonium oxalate is a chemical compound with the formula (NH4)2C2O4. It is a white, crystalline solid that is highly soluble in water. Diammonium oxalate is commonly used in analytical chemistry as a reducing agent and in various industrial processes, such as textile and leather manufacturing, where it serves as a mordant in dyeing processes. It also finds application in photography as a component in developing solutions. Additionally, diammonium oxalate has been utilized in some laboratory settings for its ability to form complexes with metal ions, aiding in their separation and analysis.