Promethium(III) oxalate

Promethium(III) oxalate is an oxalate of promethium, with the chemical formula Pm2(C2O4)3. Its decahydrate crystallizes in the monoclinic crystal system with space group P21/m. Promethium(III) oxalate trihydrate can decompose into stable basic carbonate Pm2O2CO3, and generate promethium(III) oxide at higher temperatures.

In all lanthanide oxalates, promethium(III) oxalate has the lowest solubility.