Recently we have reported the peroxidase mimicking ability of metal free brominated graphene (GBR) (Analytical Chemistry, 89, 783-791, 2017) at a pH less than 7.2. Here we report the novel catalase mimicking ability of GBR via electrochemical (electro-oxidation) detection of hydrogen peroxide (H2O2) at pH >= 7.2. We have fabricated successfully a low cost electrochemical sensor using GBR coated glassy carbon electrode (GCE) [(GBR-GCE)-working electrode] and showed its excellent cyclic voltametry (CV) response towards electro-oxidation of hydrogen peroxide (H2O2), which is so far shown by electrodes made of platinum-group metals like Pt, Ir, Ru etc. Thus, GBR has exhibited the dual mimicking ability as peroxidase and also as catalase under different conditions. A plausible mechanism of sensing of hydrogen peroxide has been proposed involving the formation of perhydroxyl radical (HO2 center dot) facilitated by GBR-GCE as the electrode. Calibration curves for H2O2 detection using both CV and differential pulse voltametry (DPV) techniques have been constructed over 0.1-10 mM linearity range with the limits of detection of 0.048 and 0.063 mM, respectively. This fabricated electrochemical sensor is highly selective, specific and its response current is least affected by the presence of interfering analytes. The results are found highly reproducible and the use of GBR has also minimized the problem and specificity associated with natural enzymes, as it can easily be stored at room temperature. Real samples have also been successfully analyzed using our fabricated sensor. (C) 2017 Elsevier Ltd. All rights reserved.