Abstract A simple and inexpensive approach to synthesizing mesoporous Fe3O4 is developed by using citric acidassisted solid thermal decomposition of ferric nitrate. The structure and magnetic property of mesoporous Fe3O4 were characterized by XRD, FT–IR, N2 adsorption–desorption isotherms, TEM, and vibrating sample magnetometer. It was shown that the decomposition of citric acid result…