During recent years, many works have been published concerning the use of boron-doped diamond (BDD) anodes in the electrolyses of synthetic and actual wastewater. Most of these works have been focused on the feasibility of the use of conductive-diamond electrochemical oxidation (CDEO) to treat different types of pollutants. Consequently, the effects of the wastewater characteristics and those of the operation conditions have been exhaustively evaluated. However, the effects of the characteristics of conductive-diamond electrodes in the bulk electrolyses results have not been discussed in detail, because the existing studies have been typically carried out using just one type of conductive-diamond surface. In this context, this work tries to clarify the role of several diamond characteristics (boron doping, sp(3)/sp(2) ratio, diamond-layer thickness, surface finishing, and substrate resistivity) on the performance of the CDEO of synthetic wastewaters polluted with phenol (as a model organic pollutant). Commercial lots provided by an important conductive-diamond manufacturing company and simple statistical tools have been used to establish the main conclusions. Results show that phenol oxidation is strongly influenced by the conductive-diamond characteristics, particularly by the roughness of the surface. The rougher the surface, the better the efficiencies obtained. These results have been interpreted in terms of the oxidation mechanisms involved in the CDEO. (C) 2008 The Electrochemical Society.