Manganese ferrite (MnFe2O4) nanosheets anchored on different weight percentages (1, 3, 5, 7 and 9%) of reduced graphene oxide (rGO) were synthesized through one-pot hydrothermal method, in which the reduction of GO and the in-situ formation of MnFe2O4 nanosheets occurred simultaneously. The prepared samples were characterized by using powder X-ray diffraction (XRD), diffuse reflectance spectroscopy (DRS), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, high resolution transmission electron microscopy (HRTEM) and selected area electron diffraction (SAED) analyses. A highly crystalline, sheet-like manganese ferrite grown on rGO was clearly observed. Electrocatalytic reduction of hydrogen peroxide (H2O2) was carried out using the GO, MnFe2O4 and rGO/MnFe2O4 composite material modified glassy carbon electrodes (GCEs). Among the different weight percentages of GO used in the preparation of rGO/MnFe2O4 nanocomposites, 5% rGO/MnFe2O4 modified GCE showed the highest catalytic current because of the presence of optimum concentration of rGO and nanostructured MnFe2O4. The effective integration of MnFe2O4 nanosheets on rGO favored the synergistic effect of MnFe2O4 and rGO on the H2O2 reduction electron transfer kinetics. The 5% rGO/MnFe2O4 modified electrode was successfully used to design an electrochemical sensor for H2O2 sensing and the detection limit was calculated to be 50 nM. The sensitivity of the 5% rGO/MnFe2O4 modified electrode was found to be 13.55 mu A cm(-2) mu M-1 using differential pulse voltammetry (DPV). Diffusion coefficient and heterogeneous rate constant for H2O2 reduction were calculated to be 1.62 x 10(-6) cm(2) s(-1) and 1.13 x 10(-3) cm s-1, respectively. In addition to good electroanalytical performance, the present sensor displayed good stability, reproducibility and acceptable anti interference ability in the presence of many-fold higher concentration of relevant interferents. The 5% rG0/MnFe2O4 nanocomposite modified electrode can be successfully used for the determination of H2O2 in real water samples. (C) 2017 Elsevier B.V. All rights reserved.