Hydrodynamic scanning electrochemical microscopy (SECM) was applied for the characterization of Pt and boron-doped diamond (BDD) macroelectrodes operated in a potential region producing reactive oxygen species (ROS) during oxygen evolution reaction (OER). Forced convection introduced by high-precision stirring enabled the formation of a stable diffusion layer of electrochemically produced species and tip-substrate voltammetry was used for the detection of different ROS species produced during OER at BDD. Hydrodynamic SECM imaging in substrate generation/tip collection mode revealed local differences in the production of the ROS species across the BDD electrode surface. (c) 2018 Elsevier Ltd. All rights reserved.