Surface oxidation processes play a key role in understanding electrochemical properties of boron-doped diamond (BDD) electrodes. The type of surface termination groups, which create the potential window of electrolytic water stability or hydrophobicity, influences such properties. In this study the kinetics of oxidation process under anodic polarization were studied in situ by means of Dynamic Electrochemical Impedance Spectroscopy (DEIS) technique. This novel approach allows for obtaining the impedance data for nonstationary systems. It has been proven that for [B] dopant level of 10k ppm, polarization to 1.5 V vs. Ag|AgCl is sufficient to initiate transformation of the film terminating BDD electrodes. XPS analysis and wettability measurements confirmed oxidation under given conditions. Boron-doped diamond (BDD) electrodes have been recently studied in-depth because of their outstanding electrochemical features which include a wide electrochemical potential window in aqueous electrolytes, 1 high anodic stability, 2 and particular electrochemical stability in harsh environments. 3,4 These properties make BDD a useful electrode material for applications in wastewater treatment, 5-7 electrochemical sensing 8-11 and electrocatalysis. 12-14 BDD is mostly synthesized by hot-filament CVD (HF CVD) 15,16 or microwave plasma-assisted CVD (MW PA CVD) and in situ doped with boron precursors. 17 The boron dopant density influences not only the electrical properties of electrode, but also its morphology and structure (sp 3 /sp 2 ratio). 6,18,19 Nevertheless, the electrochemical behavior of BDD depends on these properties. 20,21 Boron concentration has impact on the electrochemical and electrical properties of BDD electrodes. The final density of boron dopant, achieved by using microwave plasma-assisted chemical vapor deposition (MW PA CVD), ranges from 10 16 to 10 21 atomsccm −3 , for the dopant density of 2 · 10 20 the p-type semiconducting material transform to semimetal. 5 The processes occurring on the BDD semiconducting electrodes are irreversible. 22 The potential window of electrolytic water stability rises with increasing dopant concentration. Not only the dopant level but also the surface termination type (hydrogen and oxygen 23-25 and other compounds added during plasma etching, i.e. CF 4 , Cl 2 , Ar and CH 4 26 ) of boron-doped diamond electrodes is an important factor in the electrode kinetics 27 and its reversibility. 28 Many kinds of surface treatment can be utilized, including dry and wet processes such as plasma treatment or electrochemical polarization. Recently, many investigators focus on hydrogen terminations (HT-BDD) and oxygen terminations (OT-BDD). BDD films deposited by microwave plasmaassisted chemical vapor deposition mainly present HT-BDD due to using hydrogen plasma. 6,11 Transformation of HT-BDD to OT-BDD is worthy of interest. It can be achieved by oxygen plasma treatments, chemical oxidation or anodic polarization. 29,30 As a result of such transformation, different combinations of bonds can be ...