Core-shell SiO2-coated iron nanoparticles were synthesized using a one-step Stober method in the presence and absence of PEG400. The 2,4-dichlorophenol degradation and antioxidation abilities of the nanoparticles were investigated. The effects of isopropanol/H2O ratio, NaOH dosage, tetraethyl orthosilicate (TEOS) dosage, and reaction time used in the synthesis were investigated. The SiO2-coated iron nanoparticles were characterized using transmission electron microscopy, scanning electron microscopy, X-ray diffraction, and Fourier-transform infrared spectroscopy. The results showed that N-2 protection during filtration and drying were unnecessary, and the iron particle preparation was simple. The nanoparticles were stable in the presence of PEG400. The effects of isopropanol/H2O ratio and TEOS dosage on 2,4-dichlorophenol degradation and antioxidation abilities were significant, although the effects of NaOH dosage and reaction time were small. The isopropanol/H2O ratio changed the nanoparticle nucleation process, whereas NaOH dosage, TEOS dosage, and reaction time changed the mesoporous coating structure. A comparison of the removal rates of 2,4-dichlorophenol using pure iron nanoparticles and using SiO2-coated iron nanoparticles showed an improvement of about 30% using SiO2-coated iron nanoparticles, suggesting that SiO2-coated iron nanoparticles improve the antioxidation abilities and reducing capacity of iron nanoparticles; such nanoparticles could have wide applications in chlorophenol degradation. (C) 2013 Elsevier B.V. All rights reserved.