The activities of four different samples of dimensionally stable anodes (DSA) for the Cl-2 evolution reaction (CER) were analysed and compared with respect to their geometric properties. The samples were made from the same catalyst material, namely mixed oxides of TiO2 and RuO2 supported on Ti, following a preparation method in which variations in morphological features of the obtained electrodes were caused by the tensile stress imposed on each sample. The study revealed intriguing correlations between activity, surface area and characteristic morphological features. It is demonstrated that a large number of active sites facilitates high catalytic performance only conditionally, while the overall activity being highly dependent on the accessibility of the active sites to effective transport of the electrolyte, where contribution of surface morphology is crucial for product escape during gas evolution. (C) 2012 Elsevier Ltd. All rights reserved.