Epitaxial (100)-oriented diamond layer with boron doping above 10(20) cm(-3) was exposed to an RF N-2 plasma, the resulting surface structure and electrochemical characteristics were investigated. The N-2 plasma treatment was combined with in vacuo pre-heating to remove adsorbates and with surface shielding to reduce plasma-induced corrosion. X-ray photoemission spectroscopy revealed full nitrogenation of the surface with the presence of C-N and C=N bond structures. Anodic treatment in 0.1 M KOH in the oxygen evolution range generated nitrogen-oxygen bonds and carbon-oxygen functionalities which partially substitute the initial nitrogen-termination. The nitrogenated and electrochemically polarised diamond electrode exhibited higher catalytic activity to [Fe(CN)(6)](3-/4-) but slower to [Ru(NH3)(6)](3+/2+) redox reactions, as compared to an identical diamond electrode with fully oxygen-terminated surface. (C) 2011 Elsevier B.V. All rights reserved.