A simple and novel method to fill carbon nanotubes (CNTs) with Ni-Fe alloys by methylbenzene-oriented constant current electrodeposition is demonstrated. The method is based on the difference in the surface conductivity of CNTs inside and outside in electrodeposition process owing to the covering of methylbenzene. The Ni-Fe alloys filled multiwalled carbon nanotubes (MWCNTs) were characterized by transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), vibrating sample magnetometer (VSM) and atomic absorption spectroscopy (AAS), respectively. Then the Ni-Fe alloys filled MWCNTs were used as hydrazine oxidation electrocatalysts in direct hydrazine (N2H4)-air fuel cells. Cyclic voltammograms (CVs) indicated that Ni85Fe15-filled MWCNTs had superior electrocatalytic activity for hydrazine electrocatalysis than catalysts with other compositions. (c) 2013 Elsevier B.V. All rights reserved.