A range of fatty acids (C-6-C-11) coated magnetic nanoparticles were synthesized. The particle size and crystal phase of MNPs were characterized by transmission electron microscope and X-ray diffraction, respectively. The synthesized MNPs were used for adsorption of benzo(a)pyrene from water samples, the study showed that a proper chain length may accommodate BaP and/or provide enough Van der Waals interactions, so decanoic acid coated MNPs (Fe3O4@C-10) were selected for the adsorption experiments. The influences of amount of sorbent, the pH and ionic strength of sample matrix, temperature and sorption time on adsorption efficiency were investigated. The study showed that the characteristics of adtorption isotherms corresponded well with Freundlich model (R-2 = 0.988), and the theoretical maximum adsorption capacity was 63.90 ng mg(-1) calculated by Langmuir model. Combined with high-performance liquid chromatography and fluorescence detection (HPLC-FLD), a simple and effective method for adsorption and determination of BaP in water samples was developed. (C) 2015 Elsevier B.V. All rights reserved.