In this work, cobalt-doped Fe2O2CO3-reduced graphene oxide (Co@ Fe2O2CO3-rGO) nanocomposites were synthesized by using one-step electrodeposition. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction spectroscopy (XRD), X-ray photoelectron spectroscopy (XPS) and electrochemical methods were used to characterize the nanocomposites. The results showed that the Co@ Fe2O2CO3 nanoparticles with average 20-40 nm were anchored on the rGO film tightly and the resulting nanocomposites showed excellent electro-catalytic effect toward the reduction of hydrogen peroxide. The determination of hydrogen peroxide was successfully achieved in the high salinity solution (0.5 mol L-1 NaCl) and the calibration curve was observed in the range of 1.5-956 mu mol L-1 with the limit of quantitation of 1.5 mu mol L-1 and the limit of detection of 0.4 mu mol L-1. (C) The Author(s) 2017. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 License (CC BY, http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse of the work in any medium, provided the original work is properly cited. All rights reserved.