A heterogeneous Fenton catalyst, multiwalled carbon nanotubes (MWCNTs)-supported Fe3O4 nanoparticles, Fe3O4/MWCNTs was evaluated through the adsorption and degradation of a trace steroidal endocrine disrupting compound (EDC) 17 alpha-methyltestosterone (MT) in water and in the presence of H2O2, respectively. The androgenic activity of the treated water was investigated during the catalytic reactions by human androgen ELISA test. The degradation mechanism of MT by Fe3O4/MWCNTs catalysis was discussed on the basis of GC-MS analysis of the intermediates and the theoretical calculation of frontier electron densities and bond dissociation enthalpies of C-H and O-H of MT molecule. Competitive oxidation could help to understand that the adsorption of trace MT onto the catalyst was favorable to MT degradation by center dot OH, which was confirmed by electron spin resonance spin-trapping technique. The results showed that Fe3O4/MWCNTs-H2O2 system could not only degrade MT but also remove its androgenic activity. The novel catalyst would be of potential application in water treatment for removing natural and synthetic hydrophobic trace pollutants. (C) 2012 Elsevier B.V. All rights reserved.