Abstract A highly porous Fe2O3/KIT-6 with Mg substitution (MgO@Fe2O3/KIT-6) has been synthesized through a coincipient wetness impregnation of Fe and Mg into ordered mesoporous KIT-6 silica. The postreaction catalyst showed higher degradation efficiency than as-prepared catalyst for imidacloprid (IMI). Higher BET surface area, broader pore size distribution of postreaction catalyst and Mg leaching during the reaction processes might be responsible for the enhanced catalytic activities of MgO@Fe2O3/KIT-6 for the heterogeneous Fenton oxidation of IMI.