Uranyl oxalate (UO<sub>2</sub>C<sub>2</sub>O<sub>4</sub>) is a pale yellow powdered uranyl salt. It is often encountered in industrial nuclear processes at both the front and back-end of the nuclear fuel cycle. Due to its hygroscopicity, uranyl oxalate rarely exists in the dehydrated state and is usually instead found in the trihydrate form (UO<sub>2</sub>C<sub>2</sub>O<sub>4</sub>÷3H<sub>2</sub>O) at room temperature. At room temperature, the powder exhibits a monoclinic crystal structure in the P2<sub>1</sub>/c space group.
Uranyl oxalate trihydrate can be produced by the reaction of uranyl nitrate hexahydrate with oxalic acid.
Uranyl oxalate has been used in actinometers.