A straightforward and novel one-step technique for electrochemical synthesis of polypyrrole micro trunk-like shape decorated with copper nanoparticles (PpyMTs-CuNPs) is presented. The technique is based on electropolymerization and copper electrodeposition in the one-pot aqueous solution. The electrodeposited CuNPs with 30 nm in diameter have embedded on the polypyrrole micro trunk-like (PpyMTs). The synthesized PpyMTs-CuNPs were characterized by field emission scanning electron microscopy (FESEM), X-ray photoelectron spectroscopy (XRD) and electrochemical methods. The chemical structures, morphology, catalytic and electrochemical properties of the synthesized PpyMTs-CuNPs toward H2O2 were examined. The prepared PpyMTs-CuNPs increased electrocatalytic activity toward reduction of hydrogen peroxide (H2O2) and can be employed as an inexpensive and novel sensor for determination of H2O2. The initial linear part was observed ranging from 0.2 mM to 1 mM with a limit of detection of 0.9 mu m and the next linear part increased to 110 mM, having a limit of detection of 4.39 mu m (S/N of 3). Additionally, the sensor exhibited remarkable reproducibility, stability and selectivity that make PpyMTs-CuNPs a good nonenzymatic H2O2 sensor. (C) 2015 The Electrochemical Society. All rights reserved.