The presence of citric acid in decontamination waste can cause complexation of radioactive cations, resulting in interferences in their removal by various treatment processes such as chemical precipitation and ion exchange, and may pose a potential danger to the environment. Mesoporous Fe-MCM-41 molecular sieves (Si/Fe = 25, 50, 75 and 100) were synthesized hydrothermally and characterized by X-ray diffraction, N-2 adsorption studies, diffuse reflectance UV-visible spectroscopy, electron paramagnetic resonance and transmission electron microscopy to evaluate the removal of citric acid from aqueous solution by the wet peroxidation method. The effect of time, pH, Si/Fe ratios of Fe-MCM-41 and temperature has been studied to achieve efficient removal of citric acid from the aqueous solution. Unlike homogeneous Fe3+ catalysis, more mineralization of citric acid was achieved by heterogeneous catalysis with Fe-MCM-41 with the percentage removal of total organic carbon of citric acid following the order Fe-MCM-41 (Si/Fe = 25) > Fe-MCM-41 (Si/Fe = 50) > Fe-MCM-41 (Si/Fe = 75) > Fe-MCM-41 (Si/Al = 100). Moreover, it was also observed that during the reaction only a minimum amount of iron is leaching from Fe-MCM-41. (c) 2007 Society of Chemical Industry