Ammonium iron(III) oxalate trihydrate is a coordination compound and a versatile chemical reagent. It appears as a crystalline solid, known for its good solubility in water and insolubility in alcohol. This compound is highly sensitive to light, which is a key factor in its primary applications.

It is widely utilized in the field of blueprinting and photographic processes, acting as a critical light-sensitive component to produce clear, cyanotype images. In analytical chemistry, it serves as an effective precipitating agent for calcium and magnesium ions, enabling their separation and quantification in various sample solutions. Additionally, it finds extensive use in the electroplating industry and for the surface coloring of aluminum and its alloys, providing durable and uniform finishes. It also acts as a precursor for synthesizing other iron-based compounds, coordination polymers, and specialized nanomaterials.