A sensitive, accurate, free of oxygen interference electrochemical sensing approach was developed in this study for H2O2 level, an important parameter in clinical, biological and environmental fields. A boron-doped diamond (BDD) electrode was modified with mesoporous platinum (MPrPt) by electrodeposition of Pt-Cu alloy and anodic dissolution of Cu from the alloy, followed by the electropolymerization of a poly(pyrrole-3-carboxylic acid) (PPy3C) and polypyrrole (PPy) (PPy3C: PPy = 4:1, molar ratio) copolymer. SEM micrographs revealed that MPrPt irregularly spreads on the BDD surface as similar to 100 nm mesoporous and snow-flake-like nanoclusters, with a pore size of 10 similar to 15 nm, and a trace amount of remnant Cu. The resulting Pt roughness factor and the effective surface area of the MPrPt/BDD were significantly larger, and its charge-transfer resistance was much smaller than those of the Pt nanoparticle modified BDD electrode. The PPy3C-PPy/MPrPt/BDD electrode exhibited very much sensitive, selective, precise, accurate, stable, reproducible, and a wide linear range of H2O2 responses at neutral pH under ambient condition, with similar sensitivity and S/N ratio to those under nitrogen protection. The limit of detection (LOD) for H2O2 was 2 mu M, with linearity range of 5 mu M similar to 49 mM (4 orders of magnitude). The BDD substrate, MPrPt, and the PPy3C-PPy copolymer together exerted a synergic effect to the prominent sensing performance. The detection was free from endogenous oxygen interference, one of the most critical issues in microanalysis, in vivo monitoring and field applications. (C) 2016 Elsevier B.V. All rights reserved.