A Fe3O4/MoS2 nanostructure was obtained by a facile hydrothermal method. High-resolution transmission electron microscopy (HRTEM) results show the Fe3O4 nanospheres disperse well on the MoS2 nanoflake. The presence of characteristic of Fe-O and Mo-O vibrations in the Fe3O4/MoS2 FT-IR spectra indicate the Fe3O4 has been composited with MoS2 successfully. High resolution of O 1s spectrum shows the presence of three types of oxygen including lattice oxygen, hydroxyl groups and S-OH. As expected, the Fe3O4/MoS2 nanostructure modified glassy carbon electrode (GCE) has the best electrochemical activity when compared with bare, Fe3O4 or MoS2 modified GCE. The Fe3O4/MoS2 displays excellent electrocatalytic performance on nitrite and Cr(VI) in different electrolytes, respectively. The amperometric response result indicates the Fe3O4/MoS2 modified GCE can be used to determine nitrite concentration in a wide linear range of 1.0-2630 M (R-2 = 0.998) with a detection limit of 0.5 mu M. The Fe3O4/MoS2 is also an effective material for Cr(VI) detection, which is superior to the Cr(VI) sensors reported previously. (C) 2015 Published by Elsevier B.V.