Fe3O4 magnetic nanoparticles (MNPs) with diameters about 10 nm were synthesized successfully and used to remove phenol and aniline from aqueous solution. The results showed that phenol and aniline could be eliminated easily from solution under acidic and neutral conditions in the presence of MNPs and H2O2. When the concentrations of Fe3O4 MNPs and H2O2 were 5 gL(-1) and 1.2 M, respectively, phenol and aniline could be removed completely after 6 h of reaction at 308 K, and the total organic carbon (TOC) abatement efficiency for phenol and aniline were 42.79% and 40.38%. Some intermediates such as formic acid, acetic acid, fumaric acid and hydroquinone were detected during reaction. Fe3O4 MNPs exhibited good stability and reusability, also showed excellent catalysis ability to eliminate some substituted phenolic and aniline compounds from solution. Fe3O4 MNPs had good superparamagnetism and was readily separated from solution by applying an external magnetic field. Finally we proposed that phenol and aniline might be degraded by the hydroxyl free radicals (center dot OH) released from H2O2 in the presence of Fe3O4 MNPs as catalysts. (C) 2009 Elsevier B.V. All rights reserved.